Question

10 pointsl Zero Deflection A particle with charge +q and velocity W enters the region between two plates of a capacitor, which are separated by a distance d. A diagram of this setup is shown below. What is the magnitude and direction of the magnetic field that would be required for the charge to pass through the capacitor undeflected?

Answer 1

here,

the upper plate of the capacitor is connected to positive plate so it is positively charged

so, the direction of electric field lines is downwards

so, the direction of electric force must be in downward direction for positive charge

for the particle to pass undeflected , the net force must be zero

to cancel out the electrostatic force , magnetic force must be in upward direction

and velocity is to the right

using right hand rule

the direction of magnetic field is INTO THE PAGE

and

as the net force must be zero

q * u * B = q * E

B = E /u

B = ( dV /d) /u

B = (dV)/(d * u)