Question

What should be the velocity of an electron so that its momentum becomes equal to that of a photon of wavelength 5200?

Answer 1

λ=hmuλ=hmu

Momentum ,mu=hλmu=hλ

⇒6.625×10−345200×10−10⇒6.625×10−345200×10−10Kgm/sKgm/s------(i)

Momentum of electron =mu=9.108×10−31×u=mu=9.108×10−31×u------(ii)

Since both are same,therefore by (i) & (ii)

9.108×10−31×u=6.625×10−345200×10−109.108×10−31×u=6.625×10−345200×10−10

u=1400m/su=1400m/s