A long straight wire carries a certain current and produces a magnetic field of 2 x 10⁻⁴ weber/m² at a perpendicular distance of 5 cm from the wire. An electron situated at 5 cm from the wire moves with a velocity 10⁷ m/s towards the wire along perpendicular to it. The force experienced by the electron will be (charge on electron = 1.6 x 10⁻¹⁹C)

Options

(a) zero
(b) 3.2 N
(c) 3.2 x 10⁻¹⁶ N
(d) 1.6 x 10⁻¹⁶ N

Correct Answer:

3.2 x 10⁻¹⁶ N

Explanation:

Given:
Magnetic field B = 2 x 10⁻⁴ weber/m²
Velocity of electron, v = 10₇ m/s
Lortenz force F = qvB sin
= 1.6 x 10⁻¹⁹ x 10₇ x 2 x 10⁻⁴ (θ = 90⁰)
= 3.2 x 10⁻¹⁶ N