Question

The work done by an uniform magnetic field, on a moving charge is:

• A. zero because \( \vec{F} \) acts parallel to \( \vec{v} \)
• B. positive because \( \vec{F} \) acts perpendicular to \( \vec{v} \)
• C. zero because \( \vec{F} \) acts perpendicular to \( \vec{v} \)
• D. negative because \( \vec{F} \) acts parallel to \( \vec{v} \)

Hint:

The work done by a magnetic force is always zero because the force is perpendicular to the direction of motion.

Answer 1

The Correct Option is C

The force on a moving charge in a magnetic field is given by \( \vec{F} = q \vec{v} \times \vec{B} \), which is always perpendicular to the velocity \( \vec{v} \). Since the force does no work (as work is \( W = \vec{F} \cdot \vec{d} \), and the force is perpendicular to the displacement), the work done is zero.
Final Answer: \[ \boxed{\text{Zero because } \vec{F} \text{ acts perpendicular to } \vec{v}} \]