Question

A coil is placed in transverse magnet field of $0.02T$. If this coil starts shrinking at a rate of $1mm/sec$, while its radius remains $4cm$, then what is the value of induced $emf$?

• A. $2\mu V$
• B. $2.5\mu V$
• C. $5\mu V$
• D. $8\mu V$

Answer 1

Answer: (C)

$5\mu V$

$B=0.02T$

$\varphi =B.A$

$=BA$

$V=\frac{d\varphi }{dt}=\times 2\pi r\frac{dr}{dt}$

$=0.02\times 2\times \frac{22}{7}\times 4\times {10}^{-2}\times 1\times {10}^{-3}$

$\frac{0.4\times 22\times 4}{7}\mu V$

$=5\mu V$