Question

A 1.2 m wide railway track is parallel to magnetic meridian. The vertical component of earth's magnetic field is 0.5 Gauss. When a train runs on the rails at a speed of 60 Km/hr, then the induced potential difference the ends of its axle will be

• A. ${10}^{-4}$ V
• B. $2\times {10}^{-4}$ V
• C. ${10}^{-3}$ V
• D. zero

Answer 1

The correct option is C ${10}^{-3}$ V

Given : $L=1.2$ m $B=0.5\times {10}^{-4}$ T

Velocity of train $v=60$ km/hr $=60\times \frac{5}{18}$ m/s $=16.67$ m/s

$\therefore$ Emf induced $E=BvL=0.5\times {10}^{-4}\times 16.67\times 1.2={10}^{-3}$ V