$6$(a) (i) State Lenz's law and explain how this law is a consequence of conservation of energy principle. (ii) A square shaped loop of side $\displaystyle \frac{l}{2}$ is initially lying outside a region of uniform magnetic field $\displaystyle \overrightarrow{\mathrm{B}}$ as shown in the figure. The loop is moved towards right with a constant velocity $\displaystyle \overrightarrow{\mathrm{v}}$ till it goes out of the region of magnetic field. 2025_CBSE_Physics_Set_Region4_Subset_Set1_Q32__ii_p27_19

2025_CBSE_Physics_Set_Region4_Subset_Set1_Q32__ii_p27_19

(I) What will be the directions of induced current when the loop enters the field and when it leaves the field? (II) Draw the plots showing the variation of magnetic flux $\displaystyle \phi$ linked with the loop with time t and variation of induced emf E with time t. Mark the relevant values of $\displaystyle \mathrm{E}, \phi$ and t on the graphs.

OR

OR

(b) (i) Differentiate between peak and rms values of alternating current. How are they related? (ii) A current element X is connected across an ac source of emf $\displaystyle \mathrm{V}=\mathrm{V}_{0} \sin 2 \pi \nu \mathrm{t}$. It is found that the voltage leads the current in phase by $\displaystyle \frac{\pi}{2}$ radian. If element X was replaced by element Y, the voltage lags behind the current in phase by $\displaystyle \frac{\pi}{2}$ radian. (I) Identify elements X and Y by drawing phasor diagrams. (II) Obtain the condition of resonance when both elements X and Y are connected in series to the source and obtain expression for resonant frequency. What is the impedance value in this case?

Physics · Electromagnetic Induction · Lenz’s Law and Conservation of Energy