A proton and an `alpha-`particle enter a uniform magnetic field moving with the same speed. If the proton takes `25 mu s` to make 5 revolutions, then the periodic time for the `alpha-` particle would be

Options

A. `50 mu s`
B. `25 mu s`
C. `10 mu s`
D. `5 mu s`

Explanation

Time taken by to make one revolution `=25/5 =5 mu s`
As `T=(2pi m)/(qB)`
So `(T_(2))/(T_(1))=(m_(2))/(m_(1))xx(q_(1))/(q_(2))`
or `T_(2)=T_(1)(m_(2)q_(1))/(m_(1)q_(2))=(5xx4m_(1))/(m_(1))xx(q)/(22)`
`T_(2)=10 mu s`