Question

A uniform magnetic field B is directed out of the page, as shown above. A loop of wire of area 0.40 m² is in the plane of the page. At a certain instant the field has a magnitude of 3.0 T and is decreasing at the rate of 0.50 T/s. The magnitude of the induced emf in the wire loop at this instant is most nearly

(A) 0.20 V 

(B) 0.60 V 

(C) 1.2 V 

(D) 1.5 V 

(E) 2.8 V

Answer 1

The correct option is: (A) 0.20 V 

Explanation:

Use a 1 second time period, the field would decrease to 2.5 T in that time.

Then apply ε = ΔФ / t

ε = ( BA_f – BA_i ) / t … ε = A (B_f – B_i) … ε = (0.4)(3 – 2.5) / 1