Question

A beam of electrons is sent in the positive x-direction in a region with a uniform magnetic field B in the positive y-direction and a uniform electric field E in the positive z-direction.

At which of the following speeds would the electrons be deflected in the positive z-direction?

a. v > E/B

b. v = E/B

c. v < E/B

Answer 1

The speed of electron is
`v = (E)/(B)`

Option (b) is correct.

Step-by-step explanation:

Given:

A beam of electrons is sent in the positive x-direction in a region with a uniform magnetic field B in the positive y-direction and a uniform electric field E in the positive z-direction.

Electric force is given by :

⇒
`F = qE`

Magnetic force is given by :

⇒
`F = q (v * B)`

`F = qvB`

Compare both the forces,

`qvB = qE`

`v = (E)/(B)`

Therefore, the speed of electron is
`v = (E)/(B)`