Q.

A 20 m long uniform copper wire held horizontally is allowed to fall under gravity (g=10 m/s2) through a uniform horizontal magnetic field of 0.5 Gauss perpendicular to the length of the wire. The induced EMF across the wire when it travels a vertical distance of 200 m is ________ mV.           [2026]

1 2010  
2 0.210  
3 20010  
4 210  

Ans.

(1)

ε=vB

v=2gh=2×10×200=2010

ε=(2010)(0.5×10-4)20

    =2010×10-3=2010 mV