CBSE Class 12 · 2008 · Electromagnetic InductionShort Answer

A coil of area of cross-section $0.5{\mathrm{m}}^2$ is placed in a magnetic field acting normally to its plane. The field varies as $B=0.5t^2+2t$, where $B$ is in tesla and $t$ in seconds. The emf induced in the coil at $t=1\mathrm{s}$ is

(a) State Lenz's law. In a closed circuit, the induced current opposes the change in magnetic flux that produced it, in accordance with the law of conservation of energy. Justify this.
(b) A metal rod of length $2\mathrm{m}$ is rotated with a frequency of $60rev/s$ a …

(i) Define the coefficient of self-induction and obtain an expression for the self-inductance of a long solenoid of length $\ell$, area of cross-section $A$, having $N$ turns.
(ii) Calculate the self-inductance of a coil using the data obtained when an AC source of frequency …

(i) With the help of a labelled diagram, describe the principle and working of an AC generator. Hence obtain an expression for the instantaneous value of the emf generated.
(ii) The coil of an AC generator consists of $100$ turns of wire, each of area $0.5{\mathrm{m}}^2$. The r …

Consider the experimental set-up shown in the figure. This jumping-ring experiment is a demonstration of simple laws of physics: a conducting non-magnetic ring is placed over the vertical core of a solenoid, and when current is passed through the solenoid, the ring is thrown off. …

The number of turns of a solenoid is doubled without changing its length and area of cross-section. The self-inductance of the solenoid will become ____ times.