Question

If $E_1,E_2$ and $E_3$ represent respectively the kinetic energies of an electron, an alpha particle and a proton each having same de Broglie wavelength then:

• A. $E_1>E_3>E_2$
• B. $E_2>E_3>E_1$
• C. $E_1>E_2>E_3$
• D. $E_1=E_2=E_3$

Answer 1

The correct option is A $E_1>E_3>E_2$

$KE=\frac{1}{2}m{u}^2$ and $\lambda =\frac{h}{mu}$

$KE=\frac{1}{2}\cdot \frac{h^2}{m{\lambda }^2}=\frac{h^2}{2m{\lambda }^2}$

So lesser is the mass, higher is the kinetic enegy so order is

$E_1>E_3>E_2$