Electron used in an electron microscope are accelerated by a voltage of 25 kV. If the voltage is increased to 100 kV then the de Broglie wavelength associated with the electrons would

Options

A. increase by 2 times
B. decrease by 2 times
C. decrease by 4 times
D. increase by 4 times

Answer

B

Explanation

We know, `lamda = (h)/(sqrt(2mE))`
where, E = qV [q = charge of electron, V = potential difference]
`:. (lamda_(1))/(lamda_(2)) = sqrt((E_(2))/(E_(1))) = sqrt((100)/(25))`
[here, `E_(1) = 25 kV and E_(2) = 100 kv`]
or, `(lamda_(1))/(lamda_(2)) = 2 or, lamda_(2) = (lamda_(1))/(2)`
The de Broglie wavelength linked with the electrons will be half