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An electron is launched with velocity ve...

An electron is launched with velocity `vec v` in a uniform magnetic field `vec B.` The angle `theta` between `vec v and vec B` lies between 0 and `pi /2`. Its velocity vector `vec v` returns to its initial value in a time interval of

A

`(2pi m)/(eB)`

B

`(2xx2pi m)/(eB)`

C

`(pi m)/(eB)`

D

depends upon between `vec v and vec B`

Text Solution

Verified by Experts

The correct Answer is:
A
Time interval in which `vecv` returns to its initial value is
same as time period of the particle, hence the required time
`=(2pim)/(eB)`
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