Wave-Particle Duality

Question 1

Why can’t diffraction happen with particles?

Answer 1

Because the particle would either not get through the gap (too big) or just pass straight through

Question 2

What is the de Broglie equation?

Answer 2

λ = h/mv

λ - de broglie wavelength
h - planck’s constant
m - mass
v - velocity

Question 3

What two experiments show wave-particle duality?

Answer 3

Diffraction and the photoelectric effect

Question 4

What is electron diffraction?

Answer 4

• Electrons are accelerated to high velocities in a vacuum and then passed through a graphite crystal.
• As the electrons pass through the graphite crystal, they diffract like waves and produce a pattern of rings
• This provides evidence that electrons have wave properties

Question 5

How can electrons be used to investigate the spacing between atoms?

Answer 5

The electrons will diffract if the spacing is roughly the same size as the wavelength of the electrons