Question 4
(a) Define mutual inductance.
(b) State three electromagnetic devices
(c)A transformer has 300 turns in the primary coil and 100 turns in the secondary coil. If the primary coil is connected to a 230 V mains supply, calculate the voltage at the secondary.
The expected responses were:
- Mutual inductance: The establishment of an emf in a coil due to change in magnetic flux in another closely located coil.
Alternatively, Mutual inductance may be defined as that common property of two closely located coils, on account of which one coil opposes changes in current in the other. - (b) Devices based on electromagnetic principles
- Electric generator
- Motors
- Radio transmitters and receivers
- TV transmitters and receivers
- Microwave oven
- Transformers
- Mobile Telephony (Handsets, BTS’)
- Induction coils
- Door bells
- Relay
- motor car induction coils
(c) The relationship between induced e.m.f. and transformer winding turns is given by:
It was reported that majority of the candidates that attempted this question responded well, to the extent that, it can easily be considered as an area of strength of the candidates.