Ncert Exercises & Solutions

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

Choose the correct option:
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

$F_{E} = qE$
Force on the charged particle due to the magnetic field,

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

$F_{m} = q (v \times B)$
Step 2: Now,

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

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