A particle having a mass of 10⁻² kg carries a charge of 5 x 10⁻⁸C. The particle is given an initial horizontal velocity of 10⁵ m/s. In the presence of electric field E⃗ and magnetic field B⃗. To keep the particle moving in a horizontal direction, it is necessary that
(1) B⃗ should be perpendicular to the direction of velocity and E⃗ should be along the direction of velocity.
(2) Both B⃗ and E⃗ should be along the direction of velocity.
(3) Both B⃗ and E⃗ are mutually perpendicular and perpendicular to the d

Options

(a) (2) and (4)
(b) (1) and (3)
(c) (3) and (4)
(d) (2) and (3)

Correct Answer:

(2) and (3)

Explanation:

Force to the electric field acts along the direction of the electric field but force due to the magnetic field acts along a direction perpendicular to both the velocity of the charged particle and the magnetic field. Hence both statements (2) and (3) are ture. In statements (2), magnetic force is zero, so, electric force will keep the particle continue to move in horizontal direction. In statement (3), both electric and magnetic forces will be opposite to each other. If their magnitudes will be equal then t