U2.6 Wave Particle Duality

Question 1

What phenomena show electromagnetic radiation behaving like waves?

Answer 1

• Interference
• Diffraction
• Polarisation

Question 2

What phenomena show electromagnetic radiation behaving like particles?

Answer 2

• Photoelectric emission
• Line spectra

Question 3

What phenomena show electromagnetic radiation behaving like both waves and particles?

Answer 3

• Reflection
• Refraction

Question 4

What is the definition of a De Broglie wavelength?

Answer 4

The wavelength of a wave associated with a moving mass.

Question 5

What is the De Broglie wavelength equation?

Answer 5

λ = h / m x v = h / p

λ = the associated wavelength in m
h = plancks constant
m = mass in kg
v = velocity in ms^-1
p = momentum in Kgms^-1

Question 7

In a diffraction tube, what happens if the accelerating P.D. Is increased?

Answer 7

The speed of the electrons increases. By De Broglie’s equation their wavelength will decrease. Their wavelength is now smaller compared to the gap. Therefore less diffraction takes place and the rings in the diffraction pattern will get closer together.