Question

A flat coil of $500$ turns each of area $50{\text{cm}}^2$ rotates in a uniform magnetic field of $0.14{\text{Wb/m}}^2$ about an axis normal to the field at an angular speed of $150{\text{rad s}}^{-1}$. The coil has a resistance of $5\Omega$. The induced e.m.f is applied to an external resistance of $10\Omega$. The peak current through the resistance is _________$\text{A}$.

• A. 3.50
• B. 3.5

Answer 1

Answer: (A), (B)

$N=500;A=50{\text{cm}}^2=50\times {10}^{-4}{\text{m}}^2$

$B=0.14{\text{Wb/m}}^2;W=150{\text{rad s}}^{-1}$

$E_{max}=NBA\omega$

$=500\times 0.14\times 50\times {10}^{-4}\times 150$

$=25\times 14\times 15\times {10}^{-2}$

$I_{max}=\frac{E_{max}}{R^{\prime }}=\frac{25\times 14\times 15\times {10}^{-2}}{10+5}=3.5\text{A}$