Question

A wheel with ten metallic spokes each $0.50m$ long is rotated with a speed of $120rev/min$ in a plane normal to the earth's magnetic field at the place. If the magnitude of the field is $0.40G$, the induced emf between the axle and the rim of the wheel is equal to

• A. $1.256\times {10}^{-3}V$
• B. $6.28\times {10}^{-4}V$
• C. $1.256\times {10}^{-4}V$
• D. $6.28\times {10}^{-5}V$

Answer 1

The correct option is D $6.28\times {10}^{-5}V$

$e=\frac{B\omega l^2}{2}$

$=\frac{(0.4\times {10}^4)\times (2\pi \times \frac{120}{60})\times (0.5{)}^2}{2}$

$=0.628\times {10}^{-4}V$