Question

According to right hand thumb rule, in a cyclotron when magnetic field is coming out the particle should move anticlockwise but it does move clockwise, why is that so?

Answer 1

Suppose a positive ion,say a proton,enters the gap between the two dees and finds dee D1 to be negative.It gets accelerated towards dee D1D1.As it enters the dee D1D1,it does not experience any electric field due to shielding effect of the metallic dee. The perpendicular magnetic field throws it into a circular path.At the instant the proton comes out of dee D1D1,,it finds dee D1D1 positive and dee D2D2. It moves faster through D2D2 describing a larger semicircle than before. Thus if the frequency of the applied voltage is kept exactly the same as the frequency of revolution of the proton,then every time the proton reaches the gap between the two dees, the electric field is reversed and proton receives a push and finally it acquires very high energy. This is called the cyclotron’s resonance condition. The proton follows a spiral path. The accelerated proton is ejected through a window by a deflecting voltage and hits the target.


Dear student,
This is how cyclotron works.According to right hand thumb rule, in a cyclotron when magnetic field is coming out the particle should move anticlockwise.This is true in case of cyclotron also.Here out means that electrons comes out.In right hand thumb rule what we mean by 'out ' means in positive z directuon and 'in 'means negative z direction.