# Which of the following cannot be described as the advantages of moving coil permanent magnets type instrument?

Which of the following cannot be described as the advantages of moving coil permanent magnets type instrument?

### Right Answer is: They have low torque/weight ratio

#### SOLUTION

1. In moving-coil instruments, the power consumption is very small.
2. The torque to weight ratio is very high.
3. Moving-coil instruments have uniformly graduated scales.
4. The same instrument can be used both as an ammeter and a voltmeter by a suitable shunt or series-resistance (multiplier).
5. Moving-coil instruments are free from errors due to external magnetic fields since the working magnetic field strength itself is very high.
6. Very large scale deflection (300°) is possible using the “circular scale “type of instruments.
7. Damping employed in moving-coil instruments is perfect since an eddy current damping is used.
8. Due to the application of an intense polarized or unidirectional field, the stray magnetic field has no effect.