What is the wavelength of an electron moving at a velocity of 0.85*c where c is the speed of light?

Question

What is the wavelength of an electron moving at a velocity of 0.85*c where c is the speed of light?

Answer 1

At speeds much lower than the speed of light you would use the de Broglie wavelength equation:

 

λ = h/(mv)

 

However, a speed of 0.85c would require working with the relativistic version of the equation:

 

λ = [h/(mv)] √(1 - v²/c²)

 

h = Planck' constant (look it up in your textbook)

m = rest mass of electron (look it up in your textbook)

v = 0.85c

 

Plug in the numbers in appropriate units and get λ.