Quantum phenomena

Question 1

What are the four subsections in the topic of quantum phenomena?

Answer 1

photoelectricity, quantisation of electron energy levels, wave-particle duality and fluorescence.

Question 2

What piece of equipment was used to observe the photoelectric effect?

Answer 2

A charged electroscope.

Question 3

What was observed in the experiment using a charged electroscope?

Answer 3

Shining UV light on the plate discharged it but light of lower frequency didn’t discharge the plate.

Question 4

What is Planck’s equation?

Answer 4

e = hf where e is energy, h is Planck’s constant and f is frequency.

Question 5

What is DeBroglie’s equation?

Answer 5

λ = h/mv

Question 6

What is the equation for energy including the work function?

Answer 6

e = ϕ+ E_k where ϕ is the work function and E_k is kinetic energy.

Question 7

What is the equation for work function?

Answer 7

ϕ = hf_0 where ϕ is the work function, h is Planck’s constant and f_0 is the threshold frequency.

Question 8

What is the threshold frequency?

Answer 8

The lowest frequency where electrons will be emitted.

Question 9

What is the work function?

Answer 9

The minimum amount of energy requires to liberate an electron.

Question 10

What effect will increasing the intensity of incident light have on emitted electrons?

Answer 10

More electrons will be emitted.

Question 11

What effect will increasing the frequency of incident light have on emitted electrons?

Answer 11

The electrons will have more energy.

Question 12

What experiment can be used to show that light is a wave?

Answer 12

Diffraction

Question 13

What experiment can be used to show that light is a particle?

Answer 13

The photoelectric effect.

Question 14

What is the only strange particle we are concerned with at A-level?

Answer 14

Kaon

Question 15

What does the strong nuclear force act on?

Answer 15

Hadrons

Question 16

What is the photoelectric effect and how does it occur?

Answer 16

High frequency light (usually in the UV range) is incident on the surface of a metal, free electrons on the surface absorb energy from the light which causes the bonds holding them to the metal to break which releases the electrons.

Question 17

What is stopping potential?

Answer 17

The pd needed to stop the fastest moving electrons with maximum kinetic energy.

Question 18

What is the equation for kinetic energy including stopping potential?

Answer 18

E_k(max) = eV_s where E_k(max) is the maximum kinetic energy (J), e is the charge on the electron (C) and V_s is the stopping potential (V).

Question 19

What is an electronvolt defined as?

Answer 19

The kinetic energy carried by an electron after it has been accelerated from rest through a potential difference of 1 volt.

Question 20

What happens when an electron moves down an energy level?

Answer 20

It emits a photon.

Question 21

What happens when an electron moves up an energy level?

Answer 21

It absorbs a photon.

Question 22

What is ionisation energy?

Answer 22

The energy required to remove an electron from an atom from the ground state (n = 1).