Question

We convert a galvanometer into an ammeter by attaching a shunt in parallel to the galvanometer so that maximum current flows through the shunt. So, how does the galvanometer show accurate current if only a small part of the current enters it?

Answer 1

A Galvanometer can detect and measure only small amounts of current flowing through it. Therefore, it is converted into an ammeter to detect larger amounts of current. A low resistance called as the shunt resistance is connected to the galvanometer in parallel and then it gets converted into the ammeter.

The shunt divides the current into 2 parts - 1. Based on its own resistance., 2. Based on the galvanometer resistance. The current can be reliably calculated from the ratios of these resistances.

Although the shunt will add its own resistance and tolerance, it will still give acceptable current measurements.

Answer 2

A shunt divides the current in two parts based on its own resistance and galvanometer resistance. From the ratios of these , you can calculate the current to be measured. You get a multiplying factor, which you use to get the current magnitude, or calibrate the scale accordingly

However, uncertainty of measurement increases with every addition of component. The shunt resistance will have its own tolerance and uncertainty in value, which affects the measurement. Apart from this, the wires, links and connections add their own factors.

Within these limits, which are mostly acceptable, you do get sufficiently reliable results.