Could someone please show me the steps on how to arrive at the answers?? The ans

Question

Could someone please show me the steps on how to arrive at the answers?? The answers are posted below the question. I just need the step by step solution. THANKS!

A magnetic field of 0.45 Gauss is directed straight down, perpendicular to the plane of a circular coil of wire that is made up of 250 turns and has a radius of 20 cm. (a) If the coil is stretched, in a time of 15 ms, to a radius of 30 cm, calculate the emf induced in the coil during the process. (b) Assuming the resistance of the coil is a constant 25?, what is the induced current in the coil during the process? (c) What is the direction of the induced current in the coil (clockwise or counterclockwise, as viewed from above)?

Answers: (a) 0.118V; (b) 0.005A; (c) counterclockwise

Explanation / Answer

Here ,

N = 250

B = 0.45 G = 4.5 *10^-5 T

time = 15 ms = 0.015 s

Now , induced EMF = change in flux /time

induced EMF = 250 * 4.5 *10^-5 * pi*(0.3^2 - 0.2^2)/(0.015)

induced EMF = 0.118 V

b)

Uisng ohm's law

Iin = 0.118/25

Iin= 4.72 *10^-3 A

the current in the coil is 4.72 *10^-3 A

c)

Now , as the flux is increasing , the field due to induced current is oposite to the applied field ,

hence , induced field is straight up , and using right hand screw rule , current is anti-clockwise

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