A 20 m long uniform copper wire held horizontally is allowed to fall under the gravity ( g=10 ~m / s ² ) 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 travells a vertical distance of 200 m is _ _ _ _ mV.

Step-by-step solution

For a conducting wire falling in a magnetic field, induced EMF is: E = BLv After falling through height h = 200 m, velocity: v = 2gh = 2 10 200 = 4000 = 20 10 m/s Converting magnetic field: B = 0.5 Gauss = 0.5 10⁻⁴ T Induced EMF: E = (0.5 10⁻⁴) 20 20 10 = 200 10⁻⁴ 10 = 0.02 10 V = 20 10 mV