Current Electricity
CBSE Class 12 Physics · 139 board questions from this chapter; 138 listed below, 2023–2026
- A particle of mass m and charge q starts from rest and moves in an electric field E=E_0 i. After travelling a distance x in the…2026
- A wire is gradually stretched to make it 100% longer. Its resistance will increase by:2026
- Two wires of same length and same area of cross-section but made of different material of resistivities ρ_1 and ρ_2 are connected…2026
- Which of the following characteristics of electrons determines the current in the conductor?2026
- A copper wire is stretched to increase its length by 1%. Then the change in its resistance is close to2026
- A current of 1.5 A is maintained in a copper wire of length 1 m with area of cross-section 1.7 × 10^-7 m^2. The magnitude of…2026
- The resistivity ρ of a metal increases with rise in temperature because:2026
- Which of the following statements is true about mobility of charge carriers in a metal?2026
- Two heaters rated as (P_1, V) and (P_2, V) are connected in series across a dc source of V/2 volt. The power consumed by the…2026
- Assertion: The work done, in taking a unit charge around a closed loop of an electric circuit involving cells and resistors in…2026
- Assertion: In a Wheatstone bridge circuit, if we interchange the position of the cell and the galvanometer, the balance condition…2026
- Assertion: Two electric heaters of power P_1 and P_2(>P_1) are joined in series across a dc source of voltage V. The power…2026
- An electric iron rated 2‧2 kW, 220V is operated at 110 V supply. Find: (i) its resistance, and (ii) heat produced by it in 10…2026
- In the given figure, a steady current I flows through the circuit when points A and C are connected by a wire of negligible…2026
- Calculate the temperature at which the resistance of a conductor becomes 20% more than its resistance at 27 °C. The value of the…2026
- What is the order of magnitude of drift velocity of electrons in a conductor? Deduce the relation between the current flowing…2026
- A heating element using nichrome is connected to a 220 V supply. Initially it draws a current of 2.9 A. After some time, the…2026
- Why manganin is used in wire-wound standard resistors? Calculate the temperature at which the resistance of a wire increases by…2026
- Establish the relation between drift velocity of electrons (v_d) and electric current (I) in a conductor. How is v_d affected…2026
- State Kirchhoff's rules. Using these rules, find the current flowing through branch FC in the given circuit.2026
- 'Current is a scalar quantity, although we represent current with an arrow.' Explain. Derive the balance condition of a…2026
- Explain the statement: "Current is a scalar although we represent current with an arrow". Use Kirchhoff's rules to find the…2026
- The two Kirchhoff's rules are based on law of conservation of two physical quantities. Name the quantities. Find magnitude and…2026
- A student sets up the circuit as shown in the figure to find the value of unknown resistance X and records a set of readings of…2026
- (i) Derive the condition for which a Wheatstone Bridge is balanced. (ii) Determine the current in 3 Ω branch of a Wheatstone…2026
- The ratio of potential difference across A B in the circuit shown for the case (i) when switch S is closed and (ii) when S is…2025
- The figure shows the voltage (V) versus the current (I) graphs for a wire at two temperatures T_1 and T_2. One can conclude that:2025
- A wire of resistance R, connected to an ideal battery consumes a power P. If the wire is gradually stretched to double its…2025
- A 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 potential…2025
- A student has three resistors, each of resistance R. To obtain a resistance of 2/3 R, she should connect2025
- Three 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 A),…2025
- Two 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 are…2025
- The resistance of a wire of length L and radius r is R. Which one of the following would provide a wire of the same material of…2025
- A current flows through a cylindrical conductor of radius R. The current density at a point in the conductor is j=α r (along its…2025
- The effective resistance between points A and B in the given circuit is:2025
- If R_s and R_p are the equivalent resistances of n resistors, each of value R, in series and parallel combinations respectively,…2025
- Two 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 P. If the…2025
- When the switch of the circuit is turned on, the filament of the bulb glows instantaneously because:2025
- Which pair of readings of ideal voltmeter and ideal ammeter in the given circuit is possible when a suitable power source of 3 Ω…2025
- A steady current I is passed through a conductor at room temperature for time t. It is observed that its temperature rises by 0 ·…2025
- Four resistors, each of resistance R and a key K are connected as shown in the figure. The equivalent resistance between points A…2025
- A cell of emf E and internal resistance r is connected to an external variable resistance R. Plot a graph showing the variation…2025
- Two wires made of the same material have the same length ( l ) but different cross-sectional areas A_1 and A_2. They are…2025
- Find the effective resistance of the network of resistors between points A and F as shown in the figure.2025
- Find the equivalent resistance between points A and B for the network shown in the figure.2025
- n identical cells, each of e. m. f. E and internal resistance r, are connected in series. Later on it was found out that two…2025
- Calculate the value of the current passing through the battery in the given circuit diagram.2025
- Show that E=ρ j leads to Ohm's law. Write a condition in which the Ohm's law is not valid for a material.2025
- A cell of emf E and internal resistance r is connected across a resistor of variable resistance R. Show graphically the variation…2025
- A battery of emf E and internal resistance r is connected to a rheostat. When a current of 2 A is dawn from the battery, the…2025
- A wire of resistance X ohm is gradually stretched till its length becomes twice its original length. If its new resistance…2025
- What is the difference between 'velocity' and 'drift velocity' of electrons in a current-carrying conductor. A copper wire of…2025
- A 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?2025
- In the given figure, three identical bulbs P, Q and S are connected to a battery. (i) Compare the brightness of bulbs P and Q…2025
- Two wires of the same material and the same radius have their lengths in the ratio 2: 3. They are connected in parallel to a…2025
- The 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 temperature…2025
- Two batteries of emf's 3 V \& 6 V and internal resistances 0.2 Ω & 0.4 Ω are connected in parallel. This combination is connected…2025
- Define Electrical conductivity. Obtain the expression of electrical conductivity of a conductor in terms of number density and…2025
- What is the difference between 'emf' and 'terminal voltage' of a cell? Two cells of emfs E_1 and E_2 and internal resistances r_1…2025
- (i) Derive an expression for the resistivity of a conductor in terms of number density of free electrons and relaxation time.…2025
- A cell of e. m. f. E and internal resistance r is connected with a variable external resistance R and a voltmeter showing…2025
- Three cells A, B and C of emfs 2 V, 3 V and 5 V respectively are connected in parallel to each other. Their internal resistances…2025
- Define the term'drift velocity'of conduction electrons in a conductor. A conductor of length l and area of cross-section A is…2025
- Define resistivity of a conductor. Discuss its dependence on temperature of the conductor and draw a plot of resistivity of…2025
- State Kirchhoff's laws. Apply these laws to find the values of current flowing in the three branches of the given circuit.2025
- In a metallic conductor, an electron, moving due to thermal motion, suffers collisions with the heavy fixed ions but after…2025
- A circuit consisting of a capacitor C, a resistor of resistance R and an ideal battery of emf V, as shown in figure is known as…2025
- (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 ) respectively…2025
- An ammeter and a voltmeter are connected in series to a battery. Their readings are noted as 'A' and 'V' respectively. If a…2024
- A heater coil rated as ( P, V ) is cut into two equal parts. One of the parts is then connected to a battery of V volt. The power…2024
- A battery supplies 0.9 A current through a 2 Ω resistor and 0.3 A current through a 7 Ω resistor when connected one by one. The…2024
- Two charged particles P and Q, having the same charge but different masses m_P and m_Q, start from rest and travel equal…2024
- Electrons drift with speed v_d in a conductor with potential difference V across its ends. If V is reduced to (V/2), their drift…2024
- In a uniform straight wire, conduction electrons move along +x direction. Let E and j be the electric field and current density…2024
- A student is asked to connect four cells, each of emf E and internal resistance r, in series. But she/he connects one cell…2024
- Consider the circuit shown in the figure. The potential difference between points A and B is:2024
- Assertion: The temperature coefficient of resistance is positive for metals and negative for p -type semiconductors. Reason (R):…2024
- Assertion: When electrons drift in a conductor, it does not mean that all free electrons in the conductor are moving in the same…2024
- What is meant by 'relaxation time' of free electrons in a conductor? Show that the resistance of a conductor can be expressed by…2024
- Define resistivity of a conductor. How does the resistivity of a conductor depend upon the following: Number density of free…2024
- A uniform wire of length L and area of cross-section A has resistance R. The wire is uniformly stretched so that its length…2024
- An electric field E is maintained in a wire of length ' l ' and area of cross-section 'a'. Derive the relation between the…2024
- Find the temperature at which the resistance of a wire made of silver will be twice its resistance at 20^° C. Take 20^° C as the…2024
- Two batteries of emfs 6 V and 3 V and internal resistances 0 · 8 Ω and 0 · 2 Ω respectively are connected in series to an…2024
- "The electron drift speed is only a few mm / s for currents in the range of a few amperes for a given conductor." How then is…2024
- Two electric heaters have power ratings P_1 and P_2, at voltage V. They are connected in series to a dc source of voltage V. Find…2024
- Two wires A and B of different metals have their lengths in ratio 1: 2 and their radii in ratio 2:1 respectively. I-V graphs for…2024
- Find the temperature at which the resistance of a conductor increases by 25% of its value at 27 °C. The temperature coefficient…2024
- Plot a graph showing the variation of current with voltage for the material GaAs. On the graph, mark the region where: resistance…2024
- Determine the current in branches AB, AC and BC of the network shown in figure.2024
- The figure shows a circuit with three ideal batteries. Find the magnitude and direction of currents in the branches AG, BF and CD.2024
- A battery of unknown emf E and internal resistance r is connected in a circuit as shown in the figure. When the key ( K ) is…2024
- A current of 1.6 A flows through a wire when a potential difference of 1.0 V is applied across it. The length and cross-sectional…2024
- Define 'current density'. Is it a scalar or a vector? An electric field E is maintained in a metallic conductor. If n be the…2024
- (i) Define 'temperature coefficient of resistance' of a metal. (ii) Show the variation of resistivity of copper with rise in…2024
- In the given network, calculate: (i) effective resistance between points A and M, and (ii) power supplied by the battery.2024
- Find the current in branch BM in the network shown:2024
- Find the currents flowing through the branches AB and BC in the network shown.2024
- A potential difference of 1.0 V is applied across a conductor of length 5.0 m and area of cross-section 1.0 mm^2. When current of…2024
- When the terminals of a cell are connected to a conductor of resistance R, an electric current flows through the circuit. The…2024
- A battery of emf E and internal resistance r is connected to an external circuit. The potential drop within the battery is…2023
- A steady current flows through a metallic wire whose area of cross-section increases continuously from one end of the wire to the…2023
- Which one of the following is not a scalar quantity?2023
- For a metallic conductor, the correct representation of variation of resistance R with temperature T is:2023
- The current density due to drift of electrons in a conductor is given by: (symbols have their usual meanings)2023
- A current of 0.8 A flows in a conductor of 40 Ω for 1 minute. The heat produced in the conductor will be2023
- The potential difference across a cell in an open circuit is 8 V. It falls to 4 V when a current of 4 A is drawn from it. The…2023
- A cell of emf E is connected across an external resistance R. When current ' I ' is drawn from the cell, the potential difference…2023
- Two wires of equal length and radii r and 2 r are connected in series. Their resistivities are 2 ρ and ρ respectively. For the…2023
- A steady current of 8 mA flows through a wire. The number of electrons passing through a cross-section of the wire in 10 s is2023
- The SI unit of mobility of charge carriers is:2023
- A conductor of 10 Ω is connected across a 6 V ideal source. The power supplied by the source to the conductor is2023
- The number of electrons flowing through a conductor per second is 3 · 3 × 10^19. The current flowing through the conductor is:2023
- The current in a device varies with time t as I=6 t, where I is in mA and t is in s. The amount of charge that passes through the…2023
- The emf and internal resistance of a cell are E and r respectively. It is connected across an external resistance R=2 r. The…2023
- Pieces of copper and of silicon are initially at room temperature. Both are heated to temperature T. The conductivity of2023
- Which one of the following is the correct representation of variation of conductivity of a conductor with temperature?2023
- Two cells of emf E each and internal resistances r and 2 r are connected in parallel as shown in the figure. The equivalent emf…2023
- The correct graph showing the variation of the resistance (R) of a cylindrical metal wire as a function of its radius ( r ),…2023
- Assertion: When three electric bulbs of power 200 W, 100 W and 50 W are connected in series to a source, the power consumed by…2023
- Assertion: The internal resistance of a cell is constant. Reason (R): Ionic concentration of the electrolyte remains same during…2023
- Assertion: The given figure does not show a balanced Wheatstone bridge. Reason (R): For a balanced bridge small current should…2023
- Assertion: The equivalent resistance between points A and B in the given network is 2 R. Reason (R): All the resistors are…2023
- Write two differences between the emf and terminal potential difference of a cell. What is the most important precaution that one…2023
- A cell of emf E and internal resistance r is connected to a variable resistance R. Draw plots showing the variation of terminal…2023
- Two conductors, made of the same material have equal lengths but different cross-sectional areas A_1 and A_2( A_1>A_2). They are…2023
- The potential difference applied across a given conductor is doubled. How will this affect (i) the mobility of electrons and (ii)…2023
- A potential difference ( V ) is applied across a conductor of length ' L ' and cross-sectional area 'A'. How will the drift…2023
- Two identical cells, each of emf E and internal resistance r, are connected with a load resistance R, first in series and then in…2023
- A potential difference V is applied across a conductor of length l and uniform cross-section area A. How will the (i) electric…2023
- Define current density and relaxation time. Derive an expression for resistivity of a conductor in terms of number density of…2023
- Two cells of emf E_1 and E_2 and internal resistances r_1 and r_2 are connected in parallel, with their terminals of the same…2023
- A potential difference V is applied across a conductor of length l and cross- sectional area A. Briefly explain how the current…2023
- Obtain a relation between the current flowing in a conductor and drift velocity of electrons in it. Hence, obtain Ohm's law.2023
- A potential difference ' V ' is applied across a load resistor of resistance R. V and R can be varied. If the current that flows…2023
- (i) Explain how free electrons in a metal at constant temperature attain an average velocity under the action of an electric…2023
- (i) Define mobility of electrons. Give its SI units. (ii) A steady current flows through a wire AB, as shown in the figure. What…2023
- The following figure shows a circuit diagram. We can find the currents through and potential differences across different…2023
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