Practice portal › Moving Charges and Magnetism › Force on a Moving Charge
Asked in GSEB Board August 2020 · Lorentz force and work done
Idea: a charge in an electromagnetic field feels an electric force and a magnetic force at the same time; the Lorentz force is their sum.
Electric part: q⃗E — along the field for a positive charge, and present even when the charge is at rest.
Magnetic part: q(⃗v×⃗B) — perpendicular to both ⃗v and ⃗B, and zero when the charge is at rest or moves along ⃗B.
Adding them: ⃗F=q[⃗E+(⃗v×⃗B)].
The order inside the cross product matters: writing ⃗B×⃗v instead of ⃗v×⃗B reverses the magnetic force.
Reading this solution needs no sign-in. You only sign in to practise against the clock and keep your progress.
Practise this with a timer