Question

Lorentz magnetic force is acting on a particle of charge \(q\) moving with velocity \(\overset{⃗}{V}\) in magnetic field \(\overset{⃗}{B}\). The work done by this force on the charged particle is

• A. zero
• B. \(\overset{⃗}{V}\times \overset{⃗}{B}\)
• C. \(\overset{⃗}{V}\times \overset{⃗}{V}\)
• D. \(q(\overset{⃗}{V}\times \overset{⃗}{B})\)

Hint:

The force is perpendicular to the velocity.

Answer 1

The Correct Option is A

Step 1: Energy view:
Work equals the change in kinetic energy.

Step 2: Speed:
A force perpendicular to velocity changes the direction of motion but not the speed, so the kinetic energy stays the same.

Step 3: Conclusion:
Work done is zero. Option (A).

Final Answer:
The magnetic force never changes the kinetic energy. \[ \boxed{A} \]