Question 12
- State the function of each of the following parts of a modern X-ray tube:
- heater;
- high tension source
- cooling fins
- State one reason for each of the following design features of a modern X-ray tube:
- the glass envelope is highly evaluated;
- the target is a metal with a very high melting point;
- the cooling fins are located outside the glass envelope.
- In a nuclear fission reaction, a nuclide is bombarded with a neutron to produce and with additional neutrons, the energy involved in the process is Q.
[mass of = 235.044 u, mass of mass of = 140.914 u, mass of neutron = 1.009 u, 1 u = 1.66 -27kg, c = 3.0 8 ms-1 ]
- Write down the balanced nuclear reaction equation for the process.
- State with reason whether Q is absorbed or released in the process.
- Calculate the value of Q in joules.
- State three differences between nuclear fusion and nuclear fission.
Observation
Part (a): This question was popular among the candidates but unfortunately performance was fair. Many candidates stated the wrong definition.
Part (b): Performance was fair although some candidates got only one right answer.
Part (c): Performance was fair although some candidates wrongly cited nuclear bomb as an example of peaceful use of nuclear energy.
Part (d): Many candidates scored full mark allotted to this question. Some however, still found it difficult to interpret the equation. Performance was below average.
The expected answer is:
12.(a) Binding Energy
Binding energy is the minimum work/energy required to separate the nucleons of an atom.
OR
The minimum work/energy required to remove an electron from the influence of the nucleus.
(b) Required Evidences
- Not affected by electric /magnetic fields
- Can travel through a vacuum
- Travels with the speed of light
- Can be polarized
- Causes fluorescence
(c) Peaceful Uses
- Generates electricity
- Treatment of tumour
- Power submarines/rockets
Food irradiation
