An electron microscope uses electrons accelerated by a voltage of 50 kV.

Electrons are accelerated by a voltage, V = 50 kV = 50 × 103 V

Charge on an electron, e = 1.6 × 10−19 C

Mass of an electron, me = 9.11 × 10−31 kg

Wavelength of yellow light = 5.9 × 10−7 m

The kinetic energy of the electron is given as:

E = eV

= 1.6 × 10−19 × 50 × 103

= 8 × 10−15 J

De Broglie wavelength is given by the relation:

$\lambda=\frac{h}{\sqrt{2 m_{e} E}}$

$=\frac{6.6 \times 10^{-34}}{\sqrt{2 \times 9.11 \times 10^{-31} \times 8 \times 10^{-15}}}$

$=5.467 \times 10^{-12} \mathrm{~m}$

This wavelength is nearly 105 times less than the wavelength of yellow light.

The resolving power of a microscope is inversely proportional to the wavelength of light used. Thus, the resolving power of an electron microscope is nearly 105 times that of an optical microscope.