Hello, I still do not understand how come there is a negative sign in the formul

Question

Hello, I still do not understand how come there is a negative sign in the formula but there not when we do tge question. Someone said that it is because it's cancelled out with B/t, but in the question, B/t is the rate of the magnitude that increases, so it's positive not negative.

Electromagnetic Induction Q.The magnetic field betreen the pole of electromagnet is uniform at anytime, but its magnitude is increasing at the rate o P o oa TI The area of the conducting loop in the field is t20 cm and the total circuit resistance including the meter is 5.o Ca Find the induced current in the circuut. cb) the loop reelaced by one made of insulator, what effect does this have on the induced emf and induced current Given 02, T15 I el R A co s B At (120 x 10 (1) o.02 X 1 O 2.4 x IO 8 x 10 A

Explanation / Answer

You have made two mistakes in your solution

I am presenting you the correct answer

B/t= 0.02=>B=0.02t and hence

E= - d¢/dt => E= - d(B.A)/dt => E=-(120*10^-4)*0.02=-2.4*10^-4 V where negative sign just tells you that the emf induced will be such that the current produced by it will oppose the change in the magnetic field through the conducting loop.

Therefore magnitude of current will be

I= E/R => I= 2.4*10^-4 / 5 = 4.8*10^-5

For insulating loop emf and current will be zero.

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