question_answer

If the de Broglie wavelength of an electron is equal to  times the wavelength of a photon of frequency then the speed of electron is equal to-                                       [JEE Main 11-Jan-2019 Morning]

(Speed of light

Planck’s constant

Mass of electron)

A)

B)

C)

D)

Correct Answer: C

Solution :

[c] The wavelength of photon of frequency v is

(i)

The de Broglie wavelength of the electron is

[Given]