Physics (Essay) Paper 2 WASSCE (SC), 2023

Question 12

 

  1. State the function of each of the following parts of a modern X-ray tube:
    1. heater;
    2. high tension source
    3. cooling fins
  2. State one reason for each of the following design features of a modern X-ray tube:
    1. the glass envelope is highly evaluated;
    2. the target is a metal with a very high melting point;
    3. the cooling fins are located outside the glass envelope.
  3. 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 ]

    1. Write down the balanced nuclear reaction equation for the process.
    2. State with reason whether Q is absorbed or released in the process.
    3. Calculate the value of Q in joules.
    4. 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