Electromagnetic Induction MCQs for NEET — Physics Questions with Answers

The induced emf (electromotive force) in a dynamo is directly proportional to the rotational velocity of the armature. According to Faraday's Law:

\[ \text{emf} \propto \text{rotational velocity} \]

If the rotational velocity of the dynamo armature is doubled, the induced emf will also double. Therefore, if the original emf is \(E\), then the new emf when the rotational velocity is doubled will be \(2E\). Thus, the induced emf will become two times the original value.

$ I = I_0 (1 - e^{-Rt \over L}) $ $ I_\alpha = I _0 (1 -e ^{- \alpha} ) = 1.5 $ $ I1 = 1.5 (1- e -2) \Rightarrow { I_\alpha \over I_1 } = { 1 \over 1 -e^{-2} } $

$ \varepsilon = M { dI \over dt} \Rightarrow 0.005 { d \over dt } ( 10 sin 100 \pi t ) = \varepsilon _ { max } = 5 \pi $

$ I_0 = 12/6 = 2A . $ Current becomes half in time t = 0.693 L/R = 1ms

$ I_0 = { NAB \Omega \over R } $

All of the above

James Clerk Maxwell is credited with unifying electromagnetism and optics. Maxwell's equations demonstrated that electric and magnetic fields travel through space as waves moving at the speed of light. This showed that light is an electromagnetic wave, thus unifying electromagnetism and optics.

When a conducting disc of radius R rotates about its axis with an angular velocity ω, the electrons in the disc experience a centrifugal force. This leads to a potential difference between the center and the edge given by (meω^2R^2)/(2e), where me is the mass of an electron and e is the charge of an electron. This is due to the work done in moving electrons against the centrifugal force.

3.

$\begin{array}{rl}& \mathrm{e}=-\frac{\mathrm{LdI}}{\mathrm{dt}}\\ & 30=\mathrm{L}\times \frac{6}{0.3}\\ & \mathrm{L}=1.5\mathrm{H}\end{array}$

$\mathrm{U}=\frac{1}{2}{\mathrm{LI}}^2$