An aeroplane having a wing span of 40 m flies due north at a speed of $100\, ms^{-1}$ in magnetic field $5 × 10^{-5} T$ acting vertically downward. The potential difference between the tips of the wings is

0.2 V

The correct answer is Option (1) → 0.2 V

Given:

Wing span, L = 40 m

Speed of airplane, v = 100 m/s

Magnetic field, B = 5 × 10⁻⁵ T (vertically downward)

When a conductor of length L moves with velocity v perpendicular to a magnetic field B, the induced emf is given by:

$\mathcal{E} = B \, v \, L$

Here, the wings act like conductors moving perpendicular to the magnetic field:

$\mathcal{E} = (5 \times 10^{-5}) \cdot 100 \cdot 40$

$\mathcal{E} = 0.2\ \text{V}$

Answer: 0.2 V