A rod of length 1 m aligned in east-west direction falls vertically downward at a constant speed of 72 km/h at a place where the vertical component of the Earth's magnetic field is 1/2 √3 gauss and angle of dip 300. Find the potential difference between two ends of the rod.
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0.0069 x 10-4 V
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10-3 V
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36 x 10-4 V
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40 x 104 V
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0.025 x 10-4 V
B
Correct answer
Explanation
Length of rod l = 1 m, Speed v = 72 km/h = 20 m/s, Angle of dip δ = 300. A rod falling vertically along east-west direction cuts only the horizontal component of the earth's field. Vertical component of earth's field Bv = 1/2 √3 gauss = (1/2 √3) x 10- 4 T. Horizontal component of earth's field BH = Bv / tan δ = (1/2 √3)/(1 / √3) gauss = 0.5 x 10-4 T. So, the potential difference between the ends of is ε = BHvl = 0.5 x 10- 4 x 20 x 1 = 10- 3 V