Ncert Exercises & Solutions

A charged particle would continue to move with a constant velocity in a region wherein,

(a) E = 0, B ≠ 0.
(b) E ≠ 0, B ≠ 0.
(c) E ≠ 0, B = 0.
(d) E = 0, B = 0.

1. (a, c)

2. (b, d)

3. (b, c, d)

4. (c, d)

(2) Hint: Find the Lorentz in each case.

Step 1: Here, the force on the charged particle due to the electric field,

F_{E} = qE

Force on the charged particle due to the magnetic field,

F_{m} = q (v \times B)

Step 2: Now,

F_{E} = 0 if E = 0 and F_{m} = 0 if \sin θ = 0 or θ ° = 0 ° or 180 °

Hence, B ≠ 0

Also, E = 0 and B = 0 and the resultant force, q E + q (v x B) = 0. In this case E ≠ 0 and B ≠ 0.