TOPIC 13.1: QUANTUM PHYSICS
Question
Answer
The Quantum nature of radiation
13.1.1
Describe the Photoelectric effect
13.1.2
Describe the concept of a photon, and how does is
explain the photoelectric effect?
13.1.3
What experiment could be use to test the Einstein
model?
13.1.4
Light is incident on a metal surface in a vacuum. The graph below
shows the variation of the maximum kinetic energy Emax of
the electrons emitted from the surface with the frequency f of
the incident light.
Emax / eV 4
3
2
1
0
0
2
4
6
8
10
12
14
f / x 10 Hz
–1
–2
–3
–4
(b)
Use data from the graph to determine
(i)
the threshold frequency.
(2)
(ii)
a value of the Planck constant.
(2)
(iii)
the work function of the surface.
(2)
The threshold frequency of a different surface is 8.0 × 1014
Hz.
(c)
On the axes opposite, draw a line to show the variation
with frequency f of the maximum kinetic energy Emax
of the electrons emitted.
(2)
(Total 10 marks)
The Wave nature of matter
13.1.5
What is the de Broglie hypothesis ? and what is mean by
matter waves?
13.1.6
What experiment can be done to verify the de Broglie
hypothesis?
13.1.7
(a)
Explain what is meant by the de Broglie wavelength of
a particle.
(2)
(b)
Calculate the de Broglie wavelength of an electron that
has been accelerated from rest through a potential
difference of 5.0 kV.
(4)
(Total 6 marks)
An electron is accelerated from rest through a potential
difference of 850 V. For this electron
(i)
calculate the gain in kinetic energy.
(1)
(ii)
deduce that the final momentum is 1.6 × 10–23
Ns.
(2)
(iii)
determine the associated de Broglie wavelength.
(Electron charge e = 1.6 × 10–19 C, Planck
constant h = 6.6 × 10–34 J s)
Atomic spectra and atomic energy states
13.1.8
What is the laboratory procedure for producing and
observing atomic spectra (emission and absorption)?
13.1.9
How does the atomic spectra provide evidence for the
quantization of energy in atoms, in terms of energy
differences between allowed electron energy?
13.1.10
How do you calculate the wavelenghts of spectral lines
from energy level differences and vice versa?
13.1.11
What is the origin of atomic energy levels in terms of the
"electron in a box" model?
13.1.12
What is the Schrodinger model of the atom?
13.1.13
Discuss the Heisenberg uncertainty principle in regard to
position-momentum and time-energy.
TOPIC 13.2: NUCLEAR PHYSICS
Question
Answer
Nuclear Physics
13.2.1
How can the radii of nuclei be estimated
from charge particle scattering
experiments?
13.2.2
How can the masses of nuclei be
determined when using a Bainbridge
mass spectrometer?
Draw a schematic diagram of the
Bainbridge spectrometer.
13.2.3
What is one piece of evidence for the
existence of nuclear energy levels?
Radioactive Decay
13.2.4
Describe β+ decay and include the
existence of the neutrino.
13.2.5
What is the exponential fuction for
radioactive decay law?
What is the definition of the decay
constant?
13.2.6
What is derivation of the relationship
between decay constant and half-life?
13.2.7
What are the methods for measuring
the half-life of an isotope?
13.2.8
The half-life of the decay of radon-222 is 3.8
days and radon-220 has a half-life of
55 s.
(d)
(i)
Suggest three ways in
which nuclei of radon-222
differ from those of radon220.
(3)
(ii)
Define half-life.
(2)
(iii)
State the expression that
relates the activity At at
time t of a sample of a
radioactive material to its
initial activity A0 at time t
= 0 and to the decay
constant λ. Use this
expression to derive the
relationship between the
decay constant λ and the
half-life T 1 .
2
mple of a radioactive material to
its initial activity A0 at
time t = 0 and to the decay
constant λ. Use this
expression to derive the
relationship between the
decay constant λ and the
half-life T 1 .
2
(3)
(iv)
Radon-222 emits αparticles. The activity of
radon gas in a sample of
1.0 m3 of air is 4.6 Bq.
Given that 1.0 m3 of the
air contains 2.6 × 1025
molecules, determine the
ratio
number of radon - 222 atoms in 1.0 m 3 of air
number of molecules in 1.0 m 3 of air
(4)
(e)
Suggest whether radon-222 or
radon-220 presents the greater
hazard to people over a long
period of time.
(1)