# How to figure out electron wavelength?

This is a sample question in our study guide and it has me perplexed. Any advice on how to solve it?

In a transmission electron microscope, electrons are transmitted through a sample at around 70% the speed of light. What is the wavelength of these electrons? (This wavelength will determine the resolution of the microscope.)

If you wanted to increase the resolution of the microscope, would you want to transmit the electrons faster or slower? Why?

• PS i dont want the answer just how to solve it. Thanks
– Josh
Nov 8, 2017 at 0:17
• To the best of my knowledge, $\lambda = \frac{v}{f}$, where $\lambda$ is wavelength, $v$ is the speed of the wave, and $f$ is the frequency of the wave. Do you know the frequency of the wave? If you don't I'm not sure how to solve the problem. Nov 8, 2017 at 0:30

Use the de Broglie equation:

$$\lambda = \frac{h}{mv}$$

h is Planck's constant, m is the mass of the electron in kg, and v is the speed of the electron in m/s.