Chapter 1: Revision

Question 1

You should know (from classical physics and special relativity): Energy of a photon:

Answer 1

E=pc

Question 2

You should know (from classical physics and special relativity):

Energy of a classical particle (with mass)

Answer 2

E = p² /2m

Question 3

Energy of a relativistic particle

Answer 3

E = sqrt(m²c⁴+p²c²

Question 4

Describe the photoelectric effect

Answer 4

• Albert Einstein provided the explanation in 1905: • Light comes in discrete packets, called photons. • Each photon has a discrete amount of energy, E = hf where h is Planck’s constant, and f is the frequency of the photon. • A photon gives all its energy to an electron in the material. • The electron is ejected from the material if this energy exceeds the binding energy φ. • When no other scattering processes are involved the electron will escape the material with kinetic energy,

Question 5

Photoelectric effect equation:

Answer 5

E_Kmax = hbarω − φ.

Question 6

Describe compton scattering

Answer 6

Compton scattering refers to the scattering of high energy x-ray photons from free electrons. • This helped establish that photons have quantised momentum as well as quantised energy. • Monochromatic x-rays scatter from a free electron in a metallic sample. • Experiments show that the scattered x-rays have longer wavelengths. • Classical electromagnetism predicts no wavelength shift.

Question 7

Equation for compton shift in wavelength

Answer 7

Question 8

You should know that De Broglie extended to particles with mass the following expressions

Answer 8

E = hbar ω and p = hbar k

Question 9

Qualitatively describe the double slit experiment

Answer 9

Question 10

derive the fringe separation

Answer 10

Question 11

Know the uncertainty principle as it applies to simultaneous measurement of position and momentum

Answer 11