Question

Two coaxial coils are very close to each other and their mutual inductance is $5mH$. If a current $50sin500t$ is passed in one of the coils then the peak value of induced emf in the secondary coil will be

• A. $5000V$
• B. $500V$
• C. $150V$
• D. $125V$

Answer 1

The correct option is D $125V$

According to principle of mutual inductance, flux induced in coil is equa to the current flowing in coil 1

${\varphi }_2=M{i}_1$

By Faraday's laws,

$\frac{d{\varphi }_2}{dt}=M\frac{d{i}_1}{dt}$ = EMF

$\therefore EMF=5\times {10}^{-3}\frac{d}{dt}50sin500t$

$\therefore EMF=125cos500t$

So, maximum vaue of EMF would be 125 V