CBSE Class 12 Physics 2025
332 questions · 680 marks · every one with the board’s own marking-scheme answer.
Marks by chapter
Counted from the 332 questions listed below, as the 2025 papers print them. CBSE allocates marks per unit, not per chapter — this is what was observed, not an official CBSE weightage. Every year compared →
| Chapter | Marks | Share |
|---|---|---|
| Ray Optics and Optical Instruments40 questions | 97 | 14.3% |
| Current Electricity43 questions | 85 | 12.5% |
| Moving Charges and Magnetism34 questions | 73 | 10.7% |
| Dual Nature of Radiation and Matter32 questions | 61 | 9.0% |
| Electromagnetic Induction27 questions | 55 | 8.1% |
| Wave Optics24 questions | 53 | 7.8% |
| Semiconductor Electronics: Materials, Devices and Simple Circuits22 questions | 45 | 6.6% |
| Electrostatic Potential and Capacitance16 questions | 41 | 6.0% |
| Atoms18 questions | 35 | 5.1% |
| Nuclei17 questions | 32 | 4.7% |
| Electric Charges and Fields16 questions | 32 | 4.7% |
| Electromagnetic Waves17 questions | 31 | 4.6% |
| Alternating Current18 questions | 30 | 4.4% |
| Magnetism and Matter8 questions | 10 | 1.5% |
332 questions from 2025
- Q1An electric dipole of dipole moment 1.0 × 10^-12 Cm lies along x -axis. An electric field of magnitude 2.0 × 10^4 NC^-1…1 mk
- Q1A metal sheet is inserted between the plates of a parallel plate capacitor of capacitance C. If the sheet partly…1 mk
- Q1Consider two identical dipoles D_1 and D_2. Charges -q and q of dipole D_1 are located at (0,0) and (a, 0) and that of…1 mk
- Q1In the circuit shown, the charge on the left plate of 20 μ F capacitor is -50 μ C. The charge on the right plate of the…1 mk
- Q1The electric field (E) and electric potential (V) at a point inside a charged hollow metallic sphere are respectively:1 mk
- Q1The ratio of potential difference across A B in the circuit shown for the case (i) when switch S is closed and (ii)…1 mk
- Q1A beam of light of wavelength 720 nm in air enters water (refractive index =4/3 ). Its wavelength in water will be:1 mk
- Q1The figure shows the voltage (V) versus the current (I) graphs for a wire at two temperatures T_1 and T_2. One can…1 mk
- Q1A body acquires charge 8.0 × 10^-12 C. The mass of the body:1 mk
- Q1Two charges -q each are placed at the vertices A and B of an equilateral triangle ABC. If M is the mid-point of AB, the…1 mk
- Q1A wire of resistance R, connected to an ideal battery consumes a power P. If the wire is gradually stretched to double…1 mk
- Q1Two point charges Q and -q are held ' r ' distance apart in free space. A uniform electric field E is applied in the…1 mk
- Q1Two horizontal plates, separated by 1 cm, are arranged one above the other. A particle of mass 5 mg and charge 2 nC is…1 mk
- Q1Figure shows variation of Coulomb force (F) acting between two point charges with 1/(r^2), r being the separation…1 mk
- Q1A charge Q is fixed in position. Another charge q is brought near charge Q and released from rest. Which of the…1 mk
- Q1Two identical point charges are placed at the two vertices A and B of an equilateral triangle of side l. The magnitude…1 mk
- Q1In the figure curved lines represent equipotential surfaces. A charge Q is moved along different paths A, B, C and D.…1 mk
- Q2A battery of e. m. f. 12 V and internal resistance 0.5 Ω is connected to a 9.5 Ω resistor through a key. The ratio of…1 mk
- Q2The effective capacitance of the network between points A and B shown in the figure is:1 mk
- Q2A student has three resistors, each of resistance R. To obtain a resistance of 2/3 R, she should connect1 mk
- Q2Three wires A, B and C of the same material have lengths and area of cross-sections as (2 l, A/2),(l, A) and (l/2, 2…1 mk
- Q2Two conductors A and B of the same material have their lengths in the ratio 1: 2 and radii in the ratio 2: 3. If they…1 mk
- Q2A capacitor of capacitance C has reactance X in an ac circuit. If the capacitance and the frequency of the applied…1 mk
- Q2The resistance of a wire of length L and radius r is R. Which one of the following would provide a wire of the same…1 mk
- Q2A current flows through a cylindrical conductor of radius R. The current density at a point in the conductor is j=α r…1 mk
- Q2The effective resistance between points A and B in the given circuit is:1 mk
- Q2If R_s and R_p are the equivalent resistances of n resistors, each of value R, in series and parallel combinations…1 mk
- Q2The electric field at a point in a region is given by E=α (r)/(| r|^3), where α is a constant and r is the distance of…1 mk
- Q2Two wires P and Q are made of the same material. The wire Q has twice the diameter and half the length as that of wire…1 mk
- Q2When the switch of the circuit is turned on, the filament of the bulb glows instantaneously because:1 mk
- Q2Which pair of readings of ideal voltmeter and ideal ammeter in the given circuit is possible when a suitable power…1 mk
- Q3A 1 cm straight segment of a conductor carrying 1 A current in x direction lies symmetrically at origin of Cartesian…1 mk
- Q3A straight conductor is carrying a current of 2 A in +x direction along it. A uniform magnetic field B=(0.6 j+0.8 k) T…1 mk
- Q3A particle of mass m and charge q moving with velocity v i is subjected to a uniform electric field E j. The particle…1 mk
- Q3A particle having charge +q enters a uniform magnetic field B as shown in the figure. The particle will describe:1 mk
- Q3A 1 cm segment of a wire lying along x -axis carries current of 0.5 A along +x direction. A magnetic field B=(0.4 mT)…1 mk
- Q3A steady current I is passed through a conductor at room temperature for time t. It is observed that its temperature…1 mk
- Q3In a circular loop of radius R, current I enters at point A and exits at point B, as shown in the figure. The value of…1 mk
- Q3A particle of mass m and charge q moves along y -axis in a region in which a uniform magnetic field B is pointing along…1 mk
- Q3The value of magnetic field at point O in the given figure is:1 mk
- Q3Four point charges Q each, are held at the four corners of a square of side l. The amount of work done in bringing a…1 mk
- Q3A rectangular coil of area A is kept in a uniform magnetic field B such that the plane of the coil makes an angle α…1 mk
- Q3A particle with charge q moving with velocity v=v_0 i enters a region with magnetic field B=B_1 j+B_2 k. The magnitude…1 mk
- Q4An alternating current is given by I=I_0 cos (100 π) t. The least time the current takes to decrease from its maximum…1 mk
- Q4A vertically held bar magnet is dropped along the axis of a copper ring having a cut as shown in the diagram. The…1 mk
- Q4The ratio of the number of turns of the primary to the secondary coils in an ideal transformer is 20: 1. If 240 V ac is…1 mk
- Q4A circular coil of diameter 15 mm having 300 turns is placed in a magnetic field of 30 mT such that the plane of the…1 mk
- Q4A bar magnet is initially at right angles to a uniform magnetic field. The magnet is rotated till the torque acting on…1 mk
- Q4A diamagnetic substance is brought, one by one, near the north pole and the south pole of a bar magnet. It is1 mk
- Q4A charged particle gains a speed of 10^6 ms^-1, when accelerated from rest through a potential difference 10 kV. It…1 mk
- Q4The magnetic field due to a small magnetic dipole of dipole moment' M 'at a distance' r 'from the centre along the axis…1 mk
- Q4A piece of a diamagnetic material, free to move when placed in a uniform magnetic field:1 mk
- Q4A material is pushed out when placed in a uniform magnetic field. The material is1 mk
- Q4A coil has 100 turns, each of area 0.05 m^2 and total resistance 1.5 Ω. It is inserted at an instant in a magnetic…1 mk
- Q5Four resistors, each of resistance R and a key K are connected as shown in the figure. The equivalent resistance…1 mk
- Q5A soft iron rod X is allowed to fall on the two poles of a U shaped permanent magnet as shown in figure. A coil is…1 mk
- Q5A current of (10/(π)) A is maintained in a circular loop of radius 14 cm. The value of dipole moment associated with…1 mk
- Q5In the figure X is a coil wound over a hollow wooden pipe. A permanent magnet is pushed at a constant speed v from the…1 mk
- Q5Which of the following substances has magnetic permeability less than that of free space?1 mk
- Q5Which one out of the following materials is not paramagnetic?1 mk
- Q5A galvanometer can be converted into an ammeter of desired range by connecting a:1 mk
- Q5A capacitor and an inductor are connected in series across an ac source of voltage of variable frequency. The frequency…1 mk
- Q5You are required to design an air-filled solenoid of inductance 0.016 H having a length 0.81 m and radius 0.02 m. The…1 mk
- Q5Two long solenoids of radii r_1 and r_2(>r_1) and number of turns per unit length n_1 and n_2 respectively are…1 mk
- Q5The materials having negative magnetic susceptibility are:1 mk
- Q6The magnetic flux linked with a closed coil (in Wb ) varies with time t (in s ) as φ=5 t^2+4 t-2. If the resistance of…1 mk
- Q6The magnetic flux linked with a coil changes with time t as φ=(8 t^2+5 t+7), where t is in seconds and φ is in Wb. The…1 mk
- Q6A transformer is a device used for converting:1 mk
- Q6A proton and an α -particle enter with the same velocity v in a uniform magnetic field B such that v ⊥ B. The ratio of…1 mk
- Q6A voltage ν=ν_0 sin ω t applied to a circuit drives a current i=i_0 sin (ω t+φ) in the circuit. The average power…1 mk
- Q6When current in a coil changes at a steady rate from 8 A to 6 A in 4 ms, an emf of 1.5 V is induced in it. The value of…1 mk
- Q6A metal rod of length 50 cm is held vertically and moved with a velocity of 10 m / s towards east. The horizontal…1 mk
- Q6An ammeter connected in series in an ac circuit reads 10 A. The maximum value of current at any instant in the circuit…1 mk
- Q7A transformer is connected to a 200 V ac source. The transformer supplies 3000 V to a device. If the number of turns in…1 mk
- Q7The given diagram exhibits the relationship between the wavelength of the electromagnetic waves and the energy of…1 mk
- Q7The number of turns between different pairs of output terminals are shown for a step-up transformer. Input voltage of…1 mk
- Q7The electric field in space between the plates of a parallel plate capacitor (each of area 2.5 × 10^-3 m^2 ) is…1 mk
- Q7X-rays are more harmful to human beings than ultraviolet radiations because X-rays -1 mk
- Q7The dimensions of 'self-inductance' are:1 mk
- Q7Which one of the following correctly represents the change in wave characteristics (all in vacuum) from microwaves to…1 mk
- Q7A coil of an ac generator, having 100 turns and area 0.1 m^2 each, rotates at half a rotation per second in a magnetic…1 mk
- Q7Which of the following rays coming from the Sun plays an important role in maintaining the Earth's warmth?1 mk
- Q7The amplitude of electric field in an electromagnetic wave in free space is 1000 Vm^-1. The amplitude of the magnetic…1 mk
- Q7In an electromagnetic wave travelling in free space, the amplitude of magnetic field is 6.0 × 10^-4 T. The amplitude of…1 mk
- Q8Which one of the following statements is correct? Electric field due to static charges is1 mk
- Q8An ac source is connected to a resistor and an inductor in series. The voltage across the resistor and inductor are 8 V…1 mk
- Q8A beaker is filled with water (refractive index 4/3 ) upto a height H. A coin is placed at its bottom. The depth of the…1 mk
- Q8The alternating current I in an inductor is observed to vary with time t as shown in the graph for a cycle. Which one…1 mk
- Q8The speed of light in two media' 1 'and' 2 'are v_1 and v_2(>v_1) respectively. For a ray of light to undergo total…1 mk
- Q8The frequency of a photon of energy 1 · 326 eV is:1 mk
- Q8A point source is placed at the bottom of a tank containing a transparent liquid (refractive index n ) to a depth H.…1 mk
- Q8The dimensions of (μ ε)^-1, where ε is permittivity and μ is permeability of a medium, are:1 mk
- Q8The magnification produced by a spherical mirror is -2 · 0. The mirror used and the nature of the image formed will be1 mk
- Q9A source produces monochromatic light of frequency 5.0 × 10^14 Hz and the power emitted is 3.31 mW. The number of…1 mk
- Q9The stopping potential V_0 measured in a photoelectric experiment for a metal surface is plotted against frequency v of…1 mk
- Q9Two coherent waves, each of intensity I_0, produce interference pattern on a screen. The average intensity of light on…1 mk
- Q9Which of the following electromagnetic waves has photons of largest momentum?1 mk
- Q9Germanium crystal is doped at room temperature with a minute quantity of boron. The charge carriers in the doped…1 mk
- Q9A tub is filled with a transparent liquid to a height of 30.0 cm. The apparent depth of a coin lying at the bottom of…1 mk
- Q9Choose the correct statement:1 mk
- Q9In a photoelectric experiment with a material of work function 2.1 eV, the stopping potential is found to be 2.5 V. The…1 mk
- Q9The focal length of a concave mirror in air is f. When the mirror is immersed in a liquid of refractive index 5/3, its…1 mk
- Q9The plane face of a planoconvex lens is silvered. The refractive index of material and radius of curvature of the…1 mk
- Q10Out of the four options given, in which transition will the emitted photon have the maximum wavelength?1 mk
- Q10The mass numbers of two nuclei A and B are 27 and 64 respectively. The ratio of their radii ((r_A)/(r_B)) will be:1 mk
- Q10Atomic spectral emission lines of hydrogen atom are incident on a zinc surface. The lines which can emit photoelectrons…1 mk
- Q10A beam of red light and a beam of blue light have equal intensities. Which of the following statements is true?1 mk
- Q10The minimum energy required to free the electron from the ground state of the hydrogen atom is:1 mk
- Q10The de Broglie wavelength associated with an electron moving with energy 5 eV is:1 mk
- Q10Let λ_e, λ_p and λ_d be the wavelengths associated with an electron, a proton and a deuteron, all moving with the same…1 mk
- Q10The work function of a material is 2 · 21 eV. Which of the following cannot produce photoelectrons from it?1 mk
- Q10The wavelength of a photon is equal to the wavelength associated with an electron. Both will have the same value of:1 mk
- Q10A compound microscope has an objective and an eyepiece of focal lengths f_0 and f_e, respectively. To obtain a large…1 mk
- Q10A glass slab (μ=1 · 5) of thickness 6 cm is placed over a paper. The shift in the letters printed on the paper will be:1 mk
- Q11Which of the following figures correctly represent the shape of curve of binding energy per nucleon as a function of…1 mk
- Q11The energy of an electron in a hydrogen atom in ground state is -13.6 eV. Its energy in an orbit corresponding to…1 mk
- Q11Two coherent light waves, each having amplitude 'a', superpose to produce an interference pattern on a screen. The…1 mk
- Q11Which of the following is an electrical conductor at room temperature?1 mk
- Q11When the resistance measured between p and n ends of a p -n junction diode is high, it can act as a/an-1 mk
- Q11The momentum (in kg m / s ) of a photon of frequency 6.0 × 10^14 Hz is:1 mk
- Q11A p-n junction diode is forward biased. As a result,1 mk
- Q12Isotones are the nuclides having:1 mk
- Q12A long straight wire is held vertically and carries a steady current in upward direction. The shape of magnetic field…1 mk
- Q12The kinetic energy of an alpha particle is four times the kinetic energy of a proton. The ratio ((λ_α)/(λ_p)) of de…1 mk
- Q12When a p-n junction diode is forward biased1 mk
- Q12Inside a nucleus, the nuclear forces between proton and proton, proton and neutron, neutron and neutron are F_pp, F_pn…1 mk
- Q13Assertion: It is difficult to move a magnet into a coil of large number of turns when the circuit of the coil is…1 mk
- Q13Assertion: n-type semiconductor is not negatively charged. Reason (R): Neutral pentavalent impurity atom doped in…1 mk
- Q13Assertion: A charged particle is moving with velocity v in x-y plane, making an angle θ(0<θ<(π)/2) with x -axis. If a…1 mk
- Q13Assertion: In a semiconductor diode the thickness of depletion layer is not fixed. Reason (R): Thickness of depletion…1 mk
- Q13Assertion: In a reflecting telescope, the image does not have chromatic aberration. Reason (R): Chromatic aberration…1 mk
- Q13Assertion: The impurities in p-type Si are not pentavalent atoms. Reason (R): The hole density in valance band in p…1 mk
- Q14Assertion: A hole is an apparent free particle with effective positive electronic charge. Reason ( R ): A hole is not…1 mk
- Q14Assertion: During formation of a nucleus, the mass defect produced is the source of the binding energy of the nucleus.…1 mk
- Q14Assertion: A series LCR circuit behaves as a pure resistive circuit at resonance. Reason (R): At resonance, X_L=X_C…1 mk
- Q14Assertion: We cannot form a p-n junction diode by taking a slab of a p-type semiconductor and physically joining it to…1 mk
- Q14Assertion: In Bohr model of hydrogen atom, the angular momentum of an electron in n^th orbit is proportional to the…1 mk
- Q14Assertion: The deflection in a galvanometer is directly proportional to the current passing through it. Reason (R): The…1 mk
- Q14Assertion: A ray of light is incident normally on the face of a prism. The emergent ray will graze along the opposite…1 mk
- Q15Assertion: X-rays are produced when slow moving electrons are stopped by a metal target of high atomic number. Reason…1 mk
- Q15Assertion: EM waves do not require a medium for their propagation. Reason (R): EM waves are transverse waves.1 mk
- Q15Assertion: Out of Infrared and radio waves, the radio waves show more diffraction effect. Reason (R): Radio waves have…1 mk
- Q15Assertion: The Balmer series in hydrogen atom spectrum is formed when the electron jumps from higher energy state to…1 mk
- Q15Assertion: In double slit experiment if one slit is closed, diffraction pattern due to the other slit will appear on…1 mk
- Q16Assertion: The binding energy per nucleon is practically constant for mass number in the range ( 30<A<170 ). Reason…1 mk
- Q16Assertion: In an ideal step-down transformer, the electrical energy is not lost. Reason (R): In a step-down…1 mk
- Q16Assertion: For monochromatic incident radiation, the emitted photoelectrons from a given metal have speed ranging from…1 mk
- Q16Assertion: The minimum negative potential applied to the anode in a photoelectric experiment at which photoelectric…1 mk
- Q16Assertion: The potential energy of an electron revolving in any stationary orbit in a hydrogen atom is positive. Reason…1 mk
- Q16Assertion: In Rutherford's alpha particle scattering experiment, the presence of only few alpha particles at angle of…1 mk
- Q17In an intrinsic semiconductor, carrier's concentration is 5 × 10^8 m^-3. On doping with impurity atoms, the hole…2 mk
- Q17A cell of emf E and internal resistance r is connected to an external variable resistance R. Plot a graph showing the…2 mk
- Q17Two wires made of the same material have the same length ( l ) but different cross-sectional areas A_1 and A_2. They…2 mk
- Q17Find the effective resistance of the network of resistors between points A and F as shown in the figure.2 mk
- Q17Find the equivalent resistance between points A and B for the network shown in the figure.2 mk
- Q17n identical cells, each of e. m. f. E and internal resistance r, are connected in series. Later on it was found out…2 mk
- Q17Calculate the value of the current passing through the battery in the given circuit diagram.2 mk
- Q17Show that E=ρ j leads to Ohm's law. Write a condition in which the Ohm's law is not valid for a material.2 mk
- Q17A cell of emf E and internal resistance r is connected across a resistor of variable resistance R. Show graphically the…2 mk
- Q17A battery of emf E and internal resistance r is connected to a rheostat. When a current of 2 A is dawn from the…2 mk
- Q17The threshold frequency for a given metal is 3.6 × 10^14 Hz. If monochromatic radiations of frequency 6.8 × 10^14 Hz…2 mk
- Q18A point object is placed in air at a distance R / 3 in front of a convex surface of radius of curvature R, separating…2 mk
- Q18In Young's double slit experiment, the screen is moved 30 cm towards the slits. As a consequence, the fringe width of…2 mk
- Q18Find the angle of diffraction (in degrees) for first secondary maximum of the pattern due to diffraction at a single…2 mk
- Q18Find the intensity at a point on the screen in Young's double slit experiment, at which the interfering waves of…2 mk
- Q18In a double slit experiment, the two slits are 1.5 mm apart. The slits are illuminated by a mixture of lights of…2 mk
- Q18In a double slit experiment, it is observed that the angular width of one fringe formed on the screen is 0.2^°. The…2 mk
- Q18In a double-slit experiment, 6^th dark fringe is observed at a certain point of the screen. A transparent sheet of…2 mk
- Q18A current of 5 A is passing along +X direction through a wire lying along X -axis. Find the magnetic field B at a point…2 mk
- Q18In a Young's double-slit experiment, the intensity at the central maximum in the interference pattern on the screen is…2 mk
- Q18Using the mirror equation and the formula of magnification, deduce that "the virtual image produced by a convex mirror…2 mk
- Q18A wire of resistance X ohm is gradually stretched till its length becomes twice its original length. If its new…2 mk
- Q18In a diffraction experiment, the slit is illuminated by light of wavelength 600 nm. The first minimum of the pattern…2 mk
- Q18Show the refraction of light wave at a plane interface using Huygens' principle and prove Snell's law.2 mk
- Q18What is the difference between 'velocity' and 'drift velocity' of electrons in a current-carrying conductor. A copper…2 mk
- Q19Define the'distance of closest approach'. An α -particle of kinetic energy K is bombarded on a thin gold foil. Derive…2 mk
- Q19Two convex lenses A and B, each of focal length 10.0 cm, are mounted on an optical bench at 50.0 cm and 70.0 cm…2 mk
- Q19The two surfaces of a biconvex lens are of radius of curvature ' R ' each. Obtain the condition under which its focal…2 mk
- Q19Find the focal length of plano-convex lens of refractive index 1.5 and radius of curvature 10 cm when it is immersed in…2 mk
- Q19Write two differences in the patterns of double-slit interference experiment and single-slit diffraction experiment.…2 mk
- Q19A spherical convex surface of radius of curvature R separates glass (refractive index 1.5) from air. Light from a point…2 mk
- Q19A transparent solid cylindrical rod (refractive index 2/(√3) ) is kept in air. A ray of light incident on its face…2 mk
- Q19A circular coil of wire having 200 turns, each of radius 4.0 cm is placed in a horizontal plane. It carries a current…2 mk
- Q19An equiconvex lens is made of glass of refractive index 1.55. If the focal length of the lens is 15 · 0 cm, calculate…2 mk
- Q19A laser beam of wavelength 500 nm and power 5 mW strikes normally on a perfectly reflecting surface of area 1 mm^2 of a…2 mk
- Q19Two concave lenses A and B, each of focal length 8.0 cm are arranged coaxially 16 cm apart as shown in figure. An…2 mk
- Q19A voltmeter of resistance 1000 Ω can measure up to 25 V. How will you convert it so that it can read up to 250 V?2 mk
- Q19Define the term, 'distance of closest approach'. A proton of 3.95 MeV energy approaches a target nucleus Z=79 in…2 mk
- Q19The ratio of the intensities at maxima to minima in Young's double-slit experiment is 25: 9. Calculate the ratio of…2 mk
- Q19A double convex lens of glass has both faces of the same radius of curvature 17 cm. Find its focal length if it is…2 mk
- Q19A light beam converges at a point O. In the path of this beam, a concave lens of focal length 15 cm is placed at a…2 mk
- Q19A laser beam of frequency 3.0 × 10^14 Hz produces average power of 9 mW. Find (i) the energy of photon of the beam, and…2 mk
- Q20A right angled isosceles glass prism ABC is kept in contact with an equilateral triangular prism DBC as shown in the…2 mk
- Q20In Bohr's model of hydrogen atom, find the percentage change in the radius of its orbit when an electron makes a…2 mk
- Q20Why is the mass of a nucleus always less than the sum of the masses of its constituents, i.e. free neutrons and free…2 mk
- Q20Radiations of two frequencies are incident on a metal surface of work function 2.0 eV one by one. The energies of their…2 mk
- Q20Draw energy band diagrams of n -type and p-type semiconductors at temperature T>0 K. Show the donor/acceptor energy…2 mk
- Q20The threshold wavelength of a metal is 450 nm. Calculate (i) the work function of the metal in eV and (ii) the maximum…2 mk
- Q20Find the ratio of minimum to maximum wavelength of radiations emitted when electron jumps from higher energy state into…2 mk
- Q20An alpha particle and a deuterium ion are accelerated through the same potential difference. These are then directed…2 mk
- Q20An electron in Bohr model of hydrogen atom makes a transition from energy level -1.51 eV to -3.40 eV. Calculate the…2 mk
- Q20Calculate the mass of an α -particle in atomic mass unit ( u ). Given, Mass of a normal helium atom =4 · 002603 u Mass…2 mk
- Q20Prove that, in Bohr model of hydrogen atom, the time period of revolution of an electron in n^th orbit is proportional…2 mk
- Q20The energy of an electron in an orbit of Bohr hydrogen atom is-3.4 eV. Find its angular momentum.2 mk
- Q20When a neutron collides with _92^235 U, the nucleus gives _54^140 Xe and _38^94 Sr as fission products and two neutrons…2 mk
- Q20A ray of light is incident on face AB of a prism ABC with angle of prism A and emerges out from face AC. The prism is…2 mk
- Q20A light of wavelength 400 nm is incident on metal surface whose work function is 3.0 × 10^-19 J. Calculate the speed of…2 mk
- Q21Briefly explain how energy is produced in stars, giving two examples of the nuclear reactions involved.2 mk
- Q21Calculate the binding energy per nucleon (in MeV ) of a helium nucleus ( _2^4 He ). Given: m(_2^4 He)=4 · 002603 u…2 mk
- Q21A p-type Si semiconductor is made by doping an average of one dopant atom per 5 × 10^7 silicon atoms. If the number…2 mk
- Q21In the given figure, three identical bulbs P, Q and S are connected to a battery. (i) Compare the brightness of bulbs P…2 mk
- Q21Two wires of the same material and the same radius have their lengths in the ratio 2: 3. They are connected in parallel…2 mk
- Q21The threshold voltage of a silicon diode is 0.7 V. It is operated at this point by connecting the diode in series with…2 mk
- Q21The resistance of a wire at 25^° C is 10 · 0 Ω. When heated to 125^° C, its resistance becomes 10 · 5 Ω. Find (i) the…2 mk
- Q21In an n-type semiconductor electron-hole combination is a continuous process at room temperature. Yet the electron…2 mk
- Q21A tank is filled with a liquid of refractive index √2, up to a height of 30 cm. A tiny bulb is glowing at the bottom of…2 mk
- Q22Two batteries of emf's 3 V \& 6 V and internal resistances 0.2 Ω & 0.4 Ω are connected in parallel. This combination is…3 mk
- Q22Define Electrical conductivity. Obtain the expression of electrical conductivity of a conductor in terms of number…3 mk
- Q22What is the difference between 'emf' and 'terminal voltage' of a cell? Two cells of emfs E_1 and E_2 and internal…3 mk
- Q22(i) Derive an expression for the resistivity of a conductor in terms of number density of free electrons and relaxation…2 mk
- Q22A cell of e. m. f. E and internal resistance r is connected with a variable external resistance R and a voltmeter…3 mk
- Q22Three cells A, B and C of emfs 2 V, 3 V and 5 V respectively are connected in parallel to each other. Their internal…3 mk
- Q22"There is a limit to the amount of charge that can be stored on a given capacitor." Explain. A capacitor is charged by…3 mk
- Q22Define the term'drift velocity'of conduction electrons in a conductor. A conductor of length l and area of…3 mk
- Q22Define resistivity of a conductor. Discuss its dependence on temperature of the conductor and draw a plot of…3 mk
- Q22Draw the energy-band diagrams for conductors, semiconductors and insulators at T=0 K. How is an electron-hole pair…3 mk
- Q23A parallel plate capacitor has plate area A and plate separation d. Half of the space between the plates is filled with…3 mk
- Q23A particle of charge q is moving with a velocity v at a distance ' d ' from a long straight wire carrying a current ' I…3 mk
- Q23Differentiate between 'nuclear fission' and 'nuclear fusion'. Briefly discuss one example of each. Draw a graph of…3 mk
- Q23An electric field E given by: E =100 i N/C, for x>0; =-100 i N/C, for x<0 exists in a region. A right circular cylinder…3 mk
- Q23In a region of a uniform electric field E, a negatively charged particle is moving with a constant velocity v=-v_0 i…3 mk
- Q23Using Biot-Savart law, derive expression for the magnetic field ( B ) due to a circular current carrying loop at a…3 mk
- Q23A charged particle q moving with a velocity v is subjected to a uniform magnetic field B acting perpendicular to v. If…3 mk
- Q23"You cannot see a person standing on the other side of a boundary wall but can hear him." Explain with reason. Light of…3 mk
- Q23Briefly explain Einstein's photoelectric equation. Four metals with their work functions are listed below: K=2 · 3 eV,…3 mk
- Q23In which cases does a charged particle not experience a force in a magnetic field? A square loop MNPK of side ' l '…3 mk
- Q23(i) Write Biot-Savart's law in vector form. (ii) Two identical circular coils A and B, each of radius R, carrying…3 mk
- Q23Write vector form of Biot-Savart law. Two insulated long straight wires, each carrying 2 · 0 A current are kept along…3 mk
- Q23Define magnetic moment of a current-carrying coil. Write its SI unit. A coil of 60 turns and area 1.5 × 10^-3 m^3…3 mk
- Q24State Lenz's law. In the given figure: (i) Identify the machine. (ii) Name the parts P and Q and R of the machine.…3 mk
- Q24Two coils ' 1 ' and ' 2 ' are placed close to each other as shown in the figure. Find the direction of induced current…3 mk
- Q24A rectangular loop carries a current of 1 A. A straight long wire carrying 2 A current is kept near the loop in the…3 mk
- Q24Differentiate between magnetic flux through an area and magnetic field at a point. A bar magnet is held with its length…3 mk
- Q24A capacitor of plate area A and plate separation d is charged by a battery to voltage V. The battery is disconnected…3 mk
- Q24An ac source of voltage ν=ν_m sin ω t is connected to a series combination of LCR circuit. Draw the phasor diagram.…3 mk
- Q24ac voltage of frequency ω is applied across a series LCR circuit. Draw the phasor diagram and obtain the impedance of…3 mk
- Q24A ray of light is incident at an angle i on a parallel sided glass slab of thickness' d 'and gets refracted into the…3 mk
- Q24In Young's double slit experiment, the separation between the two slits is 1.0 mm and the screen is 1.0 m away from the…3 mk
- Q24Consider two long co-axial solenoids S_1 and S_2, each of length l(≫ r_2) and of radius r_1 and r_2(r_2>r_1). The…3 mk
- Q24Show that the energy required to build up the current I in a coil of inductance L is 1/2 L^2. Considering the case of…3 mk
- Q24State Faraday's law of electromagnetic induction and explain the role of negative sign in its expression. Explain, with…3 mk
- Q24State Lenz's law. A rod MN of length L is rotated about an axis passing through its end M perpendicular to its length,…3 mk
- Q24The magnetic moment ( 5 J / T ) of a bar magnet points along a uniform magnetic field 0 · 4 T. Calculate (i) the…3 mk
- Q24Differentiate between the peak value and root mean square value of an alternating current. Derive the expression for…3 mk
- Q24Obtain an expression for the self-inductance of a long solenoid of length ' l ', cross-sectional area 'A' and having '…3 mk
- Q24Answer the following, giving reasons: The maximum kinetic energy of the photoelectrons is independent of the intensity…3 mk
- Q25A right-angled prism ABC (refractive index √2 ) is kept on a plane mirror as shown in the figure. A ray of light is…3 mk
- Q25Using the Huygens' principle, briefly describe reflection of a plane wavefront from a reflecting surface. Hence, prove…3 mk
- Q25A concave mirror has radius of curvature 20 cm. Calculate the distance of an object from the mirror so as to form an…3 mk
- Q25Differentiate between half-wave and full-wave rectification. With the help of a circuit diagram, explain the working of…3 mk
- Q25The electric field E of an electromagnetic wave propagating in north direction is oscillating in up and down direction.…3 mk
- Q25How is an electromagnetic wave produced? An electromagnetic wave is travelling in vertically upward direction. At an…3 mk
- Q25Describe briefly Geiger-Marsden scattering experiment. Depict the graph showing the variation of number of scattered…3 mk
- Q25How are electromagnetic waves produced? Write the wavelength range and one use of: (i) Microwaves, and (ii) Ultraviolet…3 mk
- Q25Differentiate between 'conduction current' and 'displacement current', giving one similarity and one dissimilarity…3 mk
- Q25Name the electromagnetic wave used (i) in radar, (ii) in eye surgery and (iii) as diagnostic tool in medicine. Write…3 mk
- Q25The amplitude of a light wave becomes n times. This results in intensity of the wave becoming m times. What is the…3 mk
- Q25A parallel plate capacitor is charged by an ac source. Show that the sum of conduction current (I_c) and the…3 mk
- Q25State any three characteristics of electromagnetic waves. Briefly explain how and where the displacement current exists…3 mk
- Q26Define 'wavefront' of a light wave. A plane wavefront is refracted from a convex lens. Draw the shape of the refracted…3 mk
- Q26Draw a plot of frequency v of incident radiations as a function of stopping potential V_0 for a given photo emissive…3 mk
- Q26A double slit set-up was initially placed in a tank filled with water and the interference pattern was obtained using a…3 mk
- Q26Mention any three features of results of experiment on photoelectric effect which cannot be explained using the wave…3 mk
- Q26Answer the following giving reason: All the photo electrons do not eject with the same kinetic energy when…3 mk
- Q26An air bubble is trapped at point P(CP=1 · 75 cm) in a spherical glass ball ( n=1 · 5 ) of radius 7 cm as shown in the…3 mk
- Q26Two small solid metal balls A and B of radii R and 2 R having charge densities 2 σ and 3 σ respectively are kept far…3 mk
- Q26When a parallel beam of light enters water surface obliquely at some angle, what is the effect on the width of the…3 mk
- Q26Two concentric circular coils of radii r_1 and r_2(r_2 ≫ r) are placed coaxially with their centres coinciding. If a…3 mk
- Q26An electron of mass m and charge - e is revolving anticlockwise around the nucleus of an atom. Obtain the expression…3 mk
- Q26Draw a ray diagram showing the image formation when a concave mirror produces a real, inverted and magnified image of…3 mk
- Q26State Kirchhoff's laws. Apply these laws to find the values of current flowing in the three branches of the given…3 mk
- Q26Write the conditions under which two light waves originating from two coherent sources can interfere each other (i)…3 mk
- Q26Name the electromagnetic radiations and write their frequency range: Used to take the photograph of the bones Produced…3 mk
- Q26Define 'work function' of a metal. How can its value be determined from a graph between stopping potential and…3 mk
- Q27What are majority and minority charge carriers in an extrinsic semiconductor? A p-n junction is forward biased.…3 mk
- Q27Show the variation of binding energy per nucleon with mass number. Write the significance of the binding energy curve.…3 mk
- Q27Use Ampere's law to derive the expression for the magnetic field due to a long straight current carrying wire of…3 mk
- Q27Define'Mass defect'and'Binding energy'of a nucleus. Describe 'Fission process'on the basis of binding energy per…3 mk
- Q27A rectangular glass slab ABCD (refractive index 1.5) is surrounded by a transparent liquid (refractive index 1.25) as…3 mk
- Q27In Bohr model of hydrogen atom, an electron is revolving in second orbit. Find the value of: (i) angular momentum of…3 mk
- Q27Explain the following observations using Einstein's photoelectric equation: Photoelectric emission does not occur from…3 mk
- Q27How is the necessary force provided to an electron to keep it moving in a circular orbit according to Bohr model of…3 mk
- Q27Write the mathematical forms of three postulates of Bohr's theory of the hydrogen atom. Using them prove that, for an…3 mk
- Q27An ac source of voltage V=V_0 sin ω t is connected to a circuit element X. It is observed that the current flowing…3 mk
- Q28What are majority and minority charge carriers of p-type and n-type semiconductors? Explain briefly the formation of…3 mk
- Q28Explain the process of formation of 'depletion layer' and 'potential barrier' in a p-n junction region of a diode, with…3 mk
- Q28Draw circuit arrangement for studying V-I characteristics of a p-n junction diode. Show the shape of the…3 mk
- Q28Two point charges of -5 μ C and 2 μ C are located in free space at ( -4 cm, 0 ) and ( 6 cm, 0 ) respectively. Calculate…3 mk
- Q28Consider the so-called'D-T reaction' (Deuterium-Tritium reaction). In a thermonuclear fusion reactor, the following…3 mk
- Q29A parallel plate capacitor consists of two conducting plates kept generally parallel to each other at a distance. When…4 mk
- Q29Einstein explained photoelectric effect on the basis of Planck's quantum theory, where light travels in the form of…4 mk
- Q29A capacitor is a system of two conductors separated by an insulator. In practice, the two conductors have charges Q and…4 mk
- Q29A galvanometer is an instrument used to show the direction and strength of the current passing through it. In a…4 mk
- Q29In a metallic conductor, an electron, moving due to thermal motion, suffers collisions with the heavy fixed ions but…4 mk
- Q30A parallel plate capacitor has two parallel plates which are separated by an insulating medium like air, mica, etc.…4 mk
- Q30A thin lens is a transparent optical medium bounded by two surfaces, at least one of which should be spherical.…4 mk
- Q30A circuit consisting of a capacitor C, a resistor of resistance R and an ideal battery of emf V, as shown in figure is…4 mk
- Q30When light travels from an optically denser medium to an optically rarer medium, at the interface it is partly…4 mk
- Q30When light travels from an optically denser medium to an optically rarer medium, at the interface it is partly…4 mk
- Q30A hydrogen atom consists of an electron revolving in a circular orbit of radius r with certain velocity v around a…4 mk
- Q30Einstein explained photoelectric effect on the basis of Planck's quantum theory, where light travels in the form of…4 mk
- Q30Extrinsic semiconductors are made by doping pure or intrinsic semiconductors with suitable impurity. There are two type…4 mk
- Q30Extrinsic semiconductors are made by doping pure or intrinsic semiconductors with suitable impurity. There are two type…4 mk
- Q30When a photon of suitable frequency is incident on a metal surface, photoelectron is emitted from it. If the frequency…4 mk
- Q31(i) A parallel plate capacitor with plate area A and plate separation d has a capacitance C_0. A slab of dielectric…5 mk
- Q31(i) A small conducting sphere A of radius r charged to a potential V, is enclosed by a spherical conducting shell B of…5 mk
- Q31(i) Three batteries E_1, E_2 and E_3 of emfs and internal resistances ( 4 V, 2 Ω ), ( 2 V, 4 Ω ) and ( 6 V, 2 Ω )…5 mk
- Q32(i) An object is placed 30 cm from a thin convex lens of focal length 10 cm. The lens forms a sharp image on a screen.…5 mk
- Q32(i) Define self-inductance of a coil. Derive the expression for the energy required to build up a current I in a coil…5 mk
- Q32(i) State Lenz's law and explain how this law is a consequence of conservation of energy principle. (ii) A square…5 mk
- Q32(i) With the help of a labelled diagram, explain the principle of working of a moving coil galvanometer. Write the…5 mk
- Q32(i) Draw a ray diagram to show the image formation by a compound microscope. Obtain the expression for the total…5 mk
- Q32(i) Two point charges 5 μ C and -1 μ C are placed at points ( -3 cm, 0,0) and ( 3 cm, 0,0 ) respectively. An external…5 mk
- Q32(i) The electric field in a region is given by E=40 x i N / C. Find the amount of work done in taking a unit positive…5 mk
- Q32(i) What is the source of force acting on a current-carrying conductor placed in a magnetic field? Obtain the…5 mk
- Q33(i) Two point charges +q and -q are held at (a, 0) and ( -a, 0 ) in x-y plane. Obtain an expression for the net…5 mk
- Q33(i) Draw a ray diagram of a reflecting telescope (Cassegrain) and explain the formation of image. State two important…5 mk
- Q33(i) Write the principle of working of an ac generator. Draw its labelled diagram and explain its working. (ii) A…5 mk
- Q33(i) (1) What are coherent sources? Why are they necessary for observing a sustained interference pattern? (2) Lights…5 mk
- Q33(i) A proton moving with velocity V in a non-uniform magnetic field traces a path as shown in the figure. The path…5 mk
- Q33(i) Explain with the help of a labelled ray diagram the formation of final image by an astronomical telescope at…5 mk
- Q33(i) A thin pencil of length ( f / 4 ) is placed coinciding with the principal axis of a mirror of focal length f. The…5 mk
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