Question

An electron of mass $m_e$ and a proton of mass $m_p$ , where $m_p$ $=$ $1836$ $m_e$ are moving with the same speed . The ratio of their de Broglie wavelength i.e $\frac{{\lambda }_{\text{electron}}}{{\lambda }_{\text{proton}}}$ will be :

• A. $918$
• B. $1836$
• C. $1$
• D. $\frac{1}{1836}$

Answer 1

The correct option is B $1836$

Given , Mass of electron $=$ $m_e$
Mass of proton $=$ $m_p$
Also , $m_p$ $=$ $1836$ $m_e$

de Broglie wavelength , $\lambda$ $=$ $\frac{h}{mv}$

$\frac{{\lambda }_e}{{\lambda }_p}$ $=$ $\frac{m_p}{m_e}$ [ $\because$ The speed is same]

$\frac{{\lambda }_e}{{\lambda }_p}=\frac{1836m_e}{m_e}=1836$

So , the option (b) is correct .