Question

A flexible circular loop `20cm` in diameter lies in a magneic field with magnitude `1.0 T`, direction lies into the plane of the page as shown in Fig. 3.187. The loop is pulled at the points indicated by the arrws, forming a loop of zero area in `0.314s`.

if `R = 0,01 Omega`, the magnitude and direction of current flowing in the loop are
A. (a) `1A`, clockwise
B. (b) `1A`, anticlockwise
C. ( c) `10 A`, clockwise
D. (d) `10 A`, anticlockwise

Answer 1

Correct Answer - C
(c )
`epsilon_(av) = -(DeltaPhi_(B))/(Deltat) = -B(DeltaA)/(Deltat) = -B((-pir)^(2))/(Deltat)`
Since the flux through the loop is decreasing, the induced current must produce a field that goes into the page. Therefore, the current flows in clockwise direction
`I_(av) = (epsilon_(av) )/(R ) = (0.1)/(0.01) = 10 A`