Question

De-Broglie wavelength of an electron travelling with speed equal to 1% of the speed of light:

• A. 400 pm
• B. 120 pm
• C. 242 pm
• D. 375 pm

Answer 1

The correct option is C 242 pm

we know de-broglie's wavelength is given by
$\lambda =\frac{h}{mv}$
where, h = planck's constant
m = mass of electron
v = velocity
$v=\frac{1}{100}\times 3\times {10}^8=3\times {10}^{6}m{s}^{-1}$
$\lambda =\frac{6.6\times {10}^{-34}}{9.1\times {10}^{-31}\times 3\times {10}^6}$
$\approx 242$ pm