Question 4
- State the function of a damping force in measuring instruments.
- State two methods by which damping force is achieved in measuring instruments.
- State an advantage of a moving-coil measuring instrument over a moving-iron measuring instrument
Observation
The expected responses were;
(a) Function of a damping force in a measuring instrument
The damping force causes the pointer to settle down to its final value without oscillation.
(b) Methods by which damping force is achieved in measuring instrument
- Air dashpot damping
- Eddy current damping
(c) Advantages of moving-coil measuring instrument over moving-iron
- Uniform/linear scale
- Not affected by stray magnetic field
- Higher sensitivity
- Perfect damping achieved
Candidates that attempted this question performed poorly.