Question

A coil has $1000$ turns and $500$ $c{m}^2$ as it's area. The plane of the coil is placed at right angles to a magnetic induction field of $2\times {10}^{-5}web/m^2$. The coil is rotated through ${180}^o$ in $0.2$ seconds. The average emf induced in the coil (in milli volts) is

• A. $5$
• B. $10$
• C. $15$
• D. $20$

Answer 1

Answer: (B)

$10$

The induced emf will be given by
$emf=\frac{△\varphi }{△t}$
$=\frac{2\varphi }{t}$
$=\frac{2\times B\times A\times n}{t}$
$=\frac{2\times 2\times {10}^{-5}\times 500\times {10}^{-4}\times 1000}{0.2}$
$=10\times {10}^{-3}V=10mV$