Question

A proton beam is going from west to east and electron beam is going from east to west. Neglect the earth's magnetic field, the electron beam will be deflected

• A. towards the proton beam
• B. away from the proton beam
• C. away from the electron beam
• D. None of these

Answer 1

The correct option is A towards the proton beam

Reffer image.

Earth'snmagnetic field is in north - south direction at any place (note that:earth's magnetic south pole lies in geographically north.) due to electric attraction by protons,it experiences electric force $\left(\overrightarrow{Fe}\right)$ due East,now from lorentz force, $\overrightarrow{Fm}=q(\overrightarrow{V}\times \overrightarrow{B})$ electrons face magnetic force $\left(\overrightarrow{F}m\right)$ downwards. so the net force $\overrightarrow{F}=\overrightarrow{Fe}+\overrightarrow{Fm}$ is towards proton beam.