Define the atomic mass unit
1/12 the mass of Carbon 12
State and explain how the mass of a Helium nucleus is different from the total mass of its protons and neutrons when separated.
Separated nucleons have a greater mass compared to when they are in the nucleus because of the binding energy added to separate the nucleons
Explain why nuclei in a star have to be at a high temperature for fusion to take place.
nucleons need to be close together for fusion to take place (SNF to get involved), but the electrostatic force is repulsive and tries to stop this
if the temperature is high thenthe nuclei have enough kinetic
energy to overcome the repulsion
Describe and explain the nature of the radiation that may be emitted from an excited
nucleus of the moderator.
gamma radiation is emitted as the nucleus de-excites down discrete energy levels
to allow the nucleus to get to the ground level/state
A cola drink of mass 0.200 kg at a temperature of 3.0 oC is poured into a glass beaker.
The beaker has a mass of 0.250 kg and is initially at a temperature of 30.0 oC.
specific heat capacity of glass = 840 J kg–1 K–1
specific heat capacity of cola = 4190 J kg–1 K–1
1Show that the final temperature, Tf, of the cola drink is about 8 oC when it reaches
thermal equilibrium with the beaker.
Assume no heat is gained from or lost to the surroundings.
1) (heat supplied by glass = heat gained by cola)
(use of mg cg ∆Tg =mc cc ∆Tc)
0.250 × 840 × (30.0 – Tf) = 0.200 × 4190 × (Tf – 3.0)
(210 × 30 – 210 tf = 838 Tf – 838 × 3)
Tf = 8.4(1) (°C)
Outline what is meant by an ideal gas
molecules have negligible volume
collisions are elastic
the gas cannot be liquified
there are no interactions between molecules (except during
collisions)
the gas obeys the (ideal) gas law / obeys Boyles law etc. at all temperatures/pressures
How can you identify is th weak force is responsible for a decay
if the decay envolves both hadtrons and leptons
A nylon string used has a density of 1150 kg m–3 and a uniform diameter of 5.0 × 10–4
m.
Determine the length l of the string used given mass = 0.5kg when frequency is 110Hz
1) Mew = density * Area
1150 * Pi * (1/2 diameter)^2
2) Sub into frequency formula with calculated T and f to find l
Answer = 0.67m
How can alpha particle backscattering be used to determine an upper limit to the nuclear radius?
Backscattering occurs when α-particles approach very close to the nucleus.
If an α-particle came too close, the strong nuclear force (SNF) would act, altering the scattering.
Observations show backscattering falls off before α-particles “touch” the nucleus.
Therefore, the distance where scattering drops gives an upper limit to the nuclear radius.
The average count per minute of 2050 was determined from a measurement over a
period of 5 minutes. Explain why the student might choose to record for longer than
5 minutes when the separation is 0.90 m.
reduce the impact of random error
what material can block beta particles
Aluminium sheet
Fission and fusion are two nuclear processes in which energy can be released.
Explain why nuclei that undergo fission are restricted to a different part of the graph of binding energy against nucleons
than those that undergo fusion.
Fission occurs for atoms with a large amount of nucleons
Fission is the splitting of the nucleus and fusion is 2 nuclei joining together
Explain why the energy released per nucleon from fusion is greater than that from fission.
Energy is released when the binding energy per nucleon is increased
fusion energy is greater as the increase in binding energy is greater than increase for fission
Boyle’s law
The pressure of an ideal gas is inversely proportional to its volume, assuming a fiixed number of molecules/moles and constant temperature
How do atoms in a gas produce a line emission spectrum
Some gas atoms have enough kinetic energy to excite other atoms by collisions because the atoms have a range of speeds/kinetic energies.
This excites electrons to higher energy levels.
When the electrons de-excite to lower energy levels they emit photons with energies equal to the energy difference between the levels, producing discrete wavelengths (a line spectrum)
Explain what is meant by an equipotential surface.
A surface on which the electric potential is the same at every point, so no work is done when moving a charge along the surface
A capacitor is made from two parallel metal plates of the same area, separated by
an air gap. It is connected across a battery of constant e.m.f.
The plates are moved further apart, maintaining the same area of overlap, whilst the battery remains connected. State and explain what change, if any, occurs to
(i) the potential difference across the plates,
(ii) the capacitance of the capacitor
(iii) the charge on each plate of the capacitor,
(iv)the energy stored by the capacitor.
Potential difference remains constant as plates remain connected to constant p.d
the capacitance decrease as C is inversely proportional to distance
Charge decreases as Q = CV and Capacitance is decreasing
Energy decreases as E = 0.5CV^2 and Capacitance is decreasing
explain why fission fragments are unstable and explain what type of radiation they are likely to emit initially.
Fission fragments are likely to be above the line of stability as they are neutron rich so become neutron emitters
A nuclear reactor core is contained in a steel vessel surrounded by concrete.
State and explain the purpose of the concrete other than its structural function.
It forms a shield to
reduce the intensity of radiation
from
neutron and gamma radiation
How is nuclear waste treated and stored short term
Initially the waste is placed into an on site cooling pond via remote control. This cools the waste and the water acts as a shield to contain radiation
How is nuclear wasted treated in the long term
After around 1 - 3 years in short term treatment, the waste is significantly less active and cooler
The waste can then be vitrified and stored deep underground in steel containers
how does activity relate to half life
Activity is inversly proportional to half life
What is meant by random particle motion
All particles have a range of speeds;
This means that the motion of the particles are unpredictable;
What is meant by the capacitance of 1F
1 Coloumb per volt
