The region between x=0 and x=L is filled with uniform constant magnetic field 25(T)`hatk`. A particle of mass m=50g having positive charge q=1C and velocity `vecV_0=50sqrt3hati+50hatjms^-1` enters the region of the magnetic field. Neglect gravity throughout the question.

The value of L if the particle emerges from the region of magnetic field with its velocity `100(ms^-1)hati` is

Options

A. `20 cm`
B. `10 cm`
C. `30 cm`
D. None of these

Answer

b

Explanation

`sin 30^@=L//R`
`L=(mV_0)/(2qB) =(50xx10^-3xx100)/(2xx1xx25) =1/10m=10cm`

`L=AB+BC`
`=rcos60^@+rcos60^@=r`
`L=(mV_0)/(qB) =20cm`
`implies` This is minimum L.
For other case:
For this case L can extend upto `oo`.