Question

A hundred turns of insulated copper wire are wrapped around an iron cylinder of area ${10}^{-3}{m}^2$ and are connected to a resistor. The total resistance in the circuit is 10 ohms. If the longitudinal magnetic induction in the iron changes from 1 weber $m^{-2}$, in one direction to 1 Weber $m^{-2}$ in the opposite direction, how much charge flows through the circuit?

• A. 2 x 10^–2 C
• B. 2 x 10^–3 C
• C. 2 x 10^–4 C
• D. 2 x 10^–5 C

Answer 1

The correct option is A 2 x 10^–2 C

$dQ=\frac{d\varphi }{R}=\frac{nAdB}{R}=\frac{100\times 1\times {10}^{-3}\times 2}{10}=2\times {10}^{-2}C$