# A magnet is dropped from a height of 2.0 m above a metal ring. ?

A magnet is dropped from a height of 2.0 m above a metal ring. As the magnet passes through the center of the ring, it is aligned with the north pole of the magnet downward. The magnet has a magnetic field strength of 100 T at its poles, and the diameter of the ring is 10 cm. The resistance of the ring is 100 ohms.

a. What is the maximum emf induced in the ring?

b. What is the maximum current induced in the ring?

c. What is the direction of the current induced in the ring? (Looking down at the ring from above)

### 1 Answer

- FiremanLv 72 months ago
BY v^2 = u^2 + 2gh

=>v^2 = 0 + 2 x 9.8 x 2

=>v = √39.2

=>v = 6.26 m/s

Area of the coil (A) = 1/4πd^2 = 1/4 x 3.14 x (10 x 10^-2)^2 = 7.85 x 10^-3 m^2

BY V = -N∆BA/∆t {-ve just indicating the direction}

=>V = 1 x 100 x 7.85 x 10^-3 {as N = 1 & for t = 1 sec}

=>V = 0.785 Volt

BY V = iR

=>i = V/R = 0.785/100

=>i = 7.85 x 10^-3 Amp OR 7.85 mA (anticlockwise)

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