If the momentum of an electron is changed by pm , then the de Broglie wavelength associated with it …..

Q. If the momentum of an electron is changed by p_m , then the de Broglie wavelength associated with it changes by 0.5% . The initial momentum of electron will be

(a) p_m/200

(b) p_m/100

(c) 200p_m

(d) 100p_m

Ans: c

Sol: Wavelength , λ = h/p

Δλ/λ = −Δp/p

0.005λ / λ = p_m/p

1/200 = p_m/p

⇒ p = 200 p_m