A galvanometer is one of the most sensitive and accurate device for detecting and measuring extremely small current or potential difference. It is calibrated in millimeter
It consist of a rectangular coil of wire wound round a soft iron cylinder (armature) placed between the pole end of a magnet. The coil is pivoted so that it can rotate in the magnetic field when an electric current is passed through it. The extent of rotation is indicated by a pointer attached to the coil spring which in turn enables the strength of the current to be measured
The sensitivity of the galvanometer is its ability to detect small currents
Accuracy of the galvanometer is the ability to indicate current values very close to the true values
To increase sensitivity of the galvanometer
- The magnetic field is made stronger
- The number of turns in the rectangular coil is increased
- The spring should be made of thinner wire to enable them twist easily.
Advantages of Moving Coil Galvanometer
- It has a uniform scale
- No extra measure needs to be taken to shield the instrument from stray magnetic field, due to its strong magnetic field
- By fitting a suitable resistance, the instrument can be made to read different ranges of P.d or currents
Disadvantage
It cannot measure alternating current (A.C)
Responses