Question

A coil of area 10-3 m2 and consisting of 30 turns of wire is placed with its plane at right angles to a magnetic field of flux density 0.1 T. When the coil is withdrawn from the field a meter in series with coil indicates that a charge of 100 mC has flown around the circuit. What is the combined resistance of the coil and meter?

Answer 1

As per the given question,

Area of the coil $(A)=10^{-3}m^2$

Number of turns in the coil $(n)=30$

Flux density of the magnetic field =0.1 T

Charge $(q)=100mC$

Let the resistance in the coil is R=?

Change in flux $d\phi = N \Delta BA =30\times 0.1\times 10 =30 Tm^2$

We know that $q=\dfrac{d\phi}{R}$

Now, substituting the values,

$R=\frac{d\phi}{q}$

$\Rightarrow R=\dfrac{30 Tm^2}{100\times 10^{-3}C}$

$\Rightarrow R=300 \Omega$