Question

An electron moving with an intial velocity
V=Voî and is an a magnetic field B=Boj.
Then, its de-Broglie wavelength
1) renains constant
2) increases with time
3) decreases with time
4) first increases then decreases SPAM OR ELSE I WILL REPORT ANSWER ​

Answer 1

1) Remains constant.

Explanation:

Given,

V = Voî, B = Boj

You can find the answer if you know which direction the Lorentz force acts.

F = q(VxB)

F = qVoBo(îxj)

F = qVoBo(k)

• Lorentz force acts alone z-direction. i.e, perpendicular to the velocity of electron.
• Hence this force cannot change the velocity of electron.
• De Broglie wavelength = h/mv = remains constant.