IIT JEE , AIEEE Forum - Physics , Magnetism

pankaj10

Q. A circular coil A of 100 turns and radius 2 cm, is placed co-centrically inside another circular coil of B of 1000 turns of radius 20 cm, both being in the same plane. When the current in the coil B decreases from 5A to 3A in 0.04s, the induced enf in the coil A is : a) 1.97 mV b) 2.53mV c) 1.53mV d)1.06mV

Plz expail it elaborately.

nik_d_1

a) 1.97mv

nik_d_1

E = -d@/dt... @=phi(flux)
E=-(B due to bigger coil) * 100*area of smaller coil...
sice d radius of bigger coil is big enough than smaller coil.. so we can consider d smaller coil 2 be a t its centre...
E= -d(B1 * A2)/dt
E= -d (((100 X u0 X I) / 2 X(.2)) X (100 X pie X (.02)^2))/ dt
E=1.97 mv!!

krishna.gopal

good answer nik

beck2ham

could u please eleborate( the calculation statement) ur answer nik ??

nik_d_1

which part?

beck2ham

E= -d (((100 X u0 X I) / 2 X(.2)) X (100 X pie X (.02)^2))/ dt

I couldn't understand this.

I mean, how did u place the values???

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