Discussion Forum

A stream of electrons from a heated filament was passed between two charged plates kept at a potential difference V esu. lf e and mare charge and mass of an electron, respectively, then the value of h/λ, where λ is the wavelength  associated with electron wave) is given by

Answer:

Explanation:

As you can see in options, energy term is mentioned hence, we have to find out relation between h/λ and energy. For this, we shall use de-Broglie wavelength and kinetic energy term in eV. de-Broglie wavelength for an electron 

$(\lambda)=\frac{h}{p}$

$p=\frac{h}{\lambda}$.........(i)

Kinetic energy ofan electron = eV

As we know that , $KE=\frac{p^{2}}{2m}$

Therefore,$eV=\frac{p^{2}}{2m}$ or $p=\sqrt{meV}$ ...{ii}

From Eqs. (i) and (ii) we get 

$\frac{h}{\lambda}=\sqrt{meV}$