# A proton beam hitting a target

Electricity and Magnetism Level 4

A non-relativistic proton beam passes without deflection through a region where there are two transverse, mutually perpendicular, electric ($$E=120 ~\textrm{kV/m}$$) and magnetic ($$B=50 ~\textrm{mT}$$) fields. Then the beam strikes a grounded target. Find the force in Newtons with which the beam acts on the target if the beam current is $$I=0.8 ~ \textrm{mA}$$. Assume that the collisions with the target are inelastic.

Details and assumptions

The proton's mass and charge are: $m_{p}=1.67 \times 10^{-27}\textrm{ kg}$ $e= 1.6 \times 10^{-19} C.$

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