Q.

The de-Broglie wavelength associated with an electron, accelerated by a potential difference of 81 V is given by          [2023]

1 13.6 nm  
2 136 nm  
3 1.36 nm   
4 0.136 nm  

Ans.

(4)

The wavelength of electron using de-Broglie equation is, λe=hmv=h2meVÅ

λe=12.27VÅ=12.2781Å=12.279Å

=1.36Å  (1Å=0.1nm)

=0.136 nm