Question

A player with 3m long iron rod runs towards east with a speed of 30 km/hr. Horizontal component of earth’s magnetic field is 4 × 10^–5wb/m². If he is running with rod in horizontal (East-west) and vertical positions, then the potential difference induced between the two ends of the rod in two cases will be

• A. Zero in vertical position and 1 × 10^–3V in horizontal position
• B. 1 × 10^–3V in vertical position and zero is horizontal position
• C. Zero in both cases
• D. 1 × 10^–3V in both cases

Answer 1

Answer: (B)

1 × 10^–3V in vertical position and zero is horizontal position

Answer 2

In horizontal position rod is moving along it’s length so e = 0

In vertical position, horizontal component of earth's magnetic field is cut by rod so induced emf e = B_Hvl

∴ $e = 4 \times 10^{- 5} \times 30 \times \frac{1000}{3600} \times 3 = 10^{- 3}V$