Chapter 57 of 2363 min read

Force on a moving charge and on a current

Why this is asked: The magnetic force on a moving charge is always perpendicular to its velocity, so it can never change the charge's speed or kinetic energy, only its direction — and it's exactly zero when velocity is parallel or antiparallel to B.

This chapter is part of a paid pack

A sample of the book is free to read — the rest, including this chapter, unlocks with full access.

See pricing

Test yourself

•An electron (mass $9 \times 1 0^{- 31}$ kg and charge $1.6 \times 1 0^{- 19}$ C) moving with speed $c /100$ ( $c$ = speed of light) is injected into a magnetic field $B$ of magnitude $9 \times 1 0^{- 4}$ T perpendicular to its direction of motion. We wish to apply a uniform electric field $E$ together with the magnetic field so that the electron does not deflect from its path. Then (speed of light $c = 3 \times 1 0^{8} m s^{- 1}$ ):

Open this in the full syllabus view · Physics

ShareWhatsApp Telegram