The work done by a static magnetic force on a moving charge is:
AAlways positive
BAlways zero
CAlways negative
DDepends on the trajectory
Answer & Solution
Correct answer: B. Always zero
1. F_mag = q v × B is ALWAYS perpendicular to v.
2. So F · v = 0 ⇒ no work done by magnetic force.
3. Magnetic force can change the DIRECTION of v but not its speed (and hence not its KE).
_Source: NCERT Class 12 Physics Ch 4 §4.2 Work by Magnetic Force_
Related questions
Certain galvanometers use eddy currents to provide electromagnetic:The SI unit of inductance is the:Eddy current flow patterns are said to resemble swirling eddies in:Foucault lived from 1819 until:Who discovered eddy currents?Swirling induced currents in a metal plate are called:What in Faraday's equation represents Lenz's law?Lenz's law says the induced current opposes the change in: