Two protons are having same kinetic energy. One proton enters a uniform magnetic field at right angles ot it. Second proton enters a uniform electric field in the direction of field. After some time their de Broglie wavelengths are `lambda_1 and lambda_2` then (a) `lambda_1 = lambda_2` (b) `lambda_1 lt lambda_2` (c) `lambda_1 gt lambda_2` (d) some more information is required

Options

A. `lamda_1=lamda_2`
B. `lamda_1gtlamda_2`
C. `lamda_1ltlamda_2`
D. `lamda_1` can be greater than or less than `l_2`

Answer

D

Explanation

Speed of electron which enters into electric firld may increase or decrease while for second electron, it remains constant.
So, from `lamda=(h)/(mv')`
`lamda_1gtlamda_2` or `lamda_1ltlamda_2`