# If the momentum of an electron is changed by P, then the de Broglie wavelength associated with it changes by 0.5%. The initial momentum of electrons will be: Option 1) 400 P Option 2) Option 3) 100 P Option 4) 200 P

$p.\lambda =h\rightarrow 1\\ \therefore p.\Delta \lambda +\lambda .\Delta p=0\\ or\:p=\frac{-\lambda }{\Delta \lambda }.\Delta p$

given $\frac{\Delta \lambda }{\lambda }=0.005, \Delta p=p\\$

initial momentum is $p=\frac{-\Delta p}{0.005}=200p$

-ve sign show change will be opposite to change in wavelength

Option 1)

400 P

This option is incorrect

Option 2)

This option is incorrect

Option 3)

100 P

This option is incorrect

Option 4)

200 P

This option is correct

### Preparation Products

##### JEE Main Rank Booster 2021

This course will help student to be better prepared and study in the right direction for JEE Main..

₹ 13999/- ₹ 9999/-
##### Knockout JEE Main April 2021 (Subscription)

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 4999/-
##### Knockout JEE Main April 2021

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 22999/- ₹ 14999/-
##### Knockout JEE Main April 2022

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 34999/- ₹ 24999/-