Question 4
(a) Define the following terms:
- electric flux;
- magnetic flux.
(b) List three examples of electromagnetic devices.
(c) A transformer has 100 turns in the primary coil and 10 turns in the secondary coil. If 230 V is applied to the primary coil, calculate the voltage across the secondary coil.
The expected responses were:
(a) (i) Definition of Electric flux
Electric flux is a measure of the distribution of the electric field lines through a given area.
OR
Electric flux = flux density x surface area.
(ii) Definition of magnetic flux
Magnetic flux is a measure of the number of distribution lines of force passing through a specific area of field.
OR
Magnetic flux = flux density x surface area
(b) Examples of electromagnetic devices
- Electric bell
- Loud speaker
- Buzzer
- Transformer
- Generator
- Relay
The Chief Examiner reported that virtually all the candidates did not respond well to questions in part (a) while majority of them responded well to questions in parts (b) and (c).