Electromagnetic Induction Test

Directions For Questions

Consider a uniform metallic disc rotating through a perpendicular magnetic field $$\vec B$$ as shown in figure. Mass of the disk is $$M$$. Its radius is $$R$$ and thickness $$t$$. It is made of a material of resistivity $$\rho$$, and is rotating clockwise as shown in figure with angular speed $$\omega$$.Magnetic field is directed into the plane of the disc. Assume the region to which magnetic field is confined is a square of side $$L (L << R) $$ centered a distance $$d$$ from point O, the center of the disk. The sides of this square are horizontal and vertical.

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Find the approximate value of induced current assuming the resistance to the current is confined to the square.

Electromagnetic...

Question 1

$$2 \times 10^{-8}$$

$$4 \times 10^{-8}$$

$$8 \times 10^{-8}$$

$$2 \times 10^{-7}$$

Question 2

$$\displaystyle \dfrac{20}{3}$$ rad/s

$$\displaystyle \dfrac{10}{3}$$ rotations/s

$$\displaystyle \dfrac{40}{3}$$ rpm

None of these

Question 3

$$By\displaystyle \sqrt{\frac{2a}{k}}$$

$$By\displaystyle \sqrt{\frac{4a}{k}}$$

$$By\displaystyle \sqrt{\frac{8a}{k}}$$

$$By\displaystyle \sqrt{\frac{a}{k}}$$

Question 4

$$\displaystyle \dfrac{BL \omega dt}{\rho}$$

$$\displaystyle \dfrac{BL^2 \omega dt}{\rho}$$

$$\displaystyle \dfrac{BL^2 \omega d}{\rho}$$

$$\displaystyle \dfrac{BL \omega d^2}{\rho}$$

Question 5

$$\displaystyle \dfrac{\mu_0 ilu}{Rx}$$

$$\displaystyle \dfrac{\mu_0 ilu}{2 \pi Rx}$$

$$\displaystyle \dfrac{\mu_0 ilu}{2Rx}$$

$$\displaystyle \dfrac{\mu_0 ilu}{4 \pi Rx}$$

Question 6

$$\displaystyle 4\mu F$$

$$\displaystyle 8\mu F$$

$$\displaystyle 1\mu F$$

$$\displaystyle 2\mu F$$

Question 7

$$10 m$$

$$40 m$$

$$70 m$$

$$100 m$$

$$140 m$$

Question 8

$$Blv$$

$$B\displaystyle \dfrac{l}{\pi}v$$

$$B\displaystyle \dfrac{2l}{\pi}v$$

none of these

Question 9

The rod becomes electrically charged

The end A becomes positively charged

The end B becomes positively charged

The rod becomes hot because of Joule heating

Question 10

if $$\vec v || \vec l$$

if $$\vec v || \vec B$$

if $$\vec l || \vec B$$

none of these

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