Physics

Problem

a. (i) Show that a charged particle passes undeflected through mutually perpendicular uniform electric field

E

and magnetic field

B

only if its speed

v

satisfies

v=E/B

. b. (ii) Three particles enter such a region: A: proton, speed

2.0\times10^{6}\,\text{m s}^{-1}

B: electron, speed

3.0\times10^{6}\,\text{m s}^{-1}

C: doubly ionised helium nucleus (alpha particle), speed

3.0\times10^{6}\,\text{m s}^{-1}

The fields are adjusted so that

E/B = 3.0\times10^{6}\,\text{m s}^{-1}

. Identify which particle(s) will emerge without deflection.