2.6 Wave Particle Duality

Question 1

Which phenomena and their experiments prove EM radiation can be explained as a wave (3)

Answer 1

Interference : Youngs d slit
Diffraction : diffraction grating
Polarisation : 2x Polaroids

Question 2

Which phenomenon can explain EM radiation as a particle

Answer 2

Photoelectric effect

Question 3

What can the wave theory not explain about the behaviour of light during the photoelectric effect (4)

Answer 3

Existence of Threshold f
Intensity of radiation having no effect below threshold f
The increase in ke of e as f increases above threshold f
No delay between radiation hitting e and it being emitted

Question 4

Which aspects of EM radiation can be explained by both (2)

Answer 4

Reflection
Refraction

Question 5

In what situation can a particle only be explained in terms of a wave

Answer 5

Electron diffraction

Question 6

De Broglie wave equation

Answer 6

& = h/p

p = momentum (m v)

Question 7

Describe electron diffraction (5)

Answer 7

e released by thermionic emission
e accelerated and incident on graphite crystal in vacuum
e diffract after passing through crystal
setting up interference pattern on fluorescent screen
Where there is cons interference, concentric rings are observed

Question 8

Will the d of circles increase or decrease as electrons get faster and why

Answer 8

Decrease
& proportional to v
& less similar to gap width
Less diffraction
Decrease in circle d

Question 9

What is the mass of an electron

Answer 9

9.11x10^-31 kg

Question 10

What do you do if you want the particles (e) to accelerate in electron diffraction experiment

Answer 10

Increase in pd

Question 11

What is the de Broglie wavelength (definition)

Answer 11

Wavelength of a matter wave associated with a moving mass