Question

To convert a galvanometer into an ammeter, we use:

• A. High resistance in series
• B. Low resistance in series
• C. High resistance in parallel
• D. Shunt wire in parallel

Hint:

• Ammeter \(\rightarrow\) Low resistance
• Voltmeter \(\rightarrow\) High resistance
• Ammeter is made by connecting shunt resistance in parallel.

Answer 1

The Correct Option is D

Concept: A galvanometer is a sensitive instrument used to detect small electric currents. To measure large currents, the galvanometer is converted into an ammeter by connecting a very small resistance called shunt resistance in parallel with it. The shunt allows most of the current to bypass the galvanometer, protecting it from damage.

Step 1: Understand the purpose of an ammeter.
An ammeter is used to measure electric current in a circuit. An ideal ammeter should have: \[ \text{Very low resistance} \] so that it does not change the current in the circuit.

Step 2: Why galvanometer alone cannot be used.
A galvanometer has finite resistance and can measure only very small currents. If large current passes through it directly, the coil may get damaged. Therefore, most current must be diverted away from the galvanometer.

Step 3: Use of shunt resistance.
A low resistance wire called shunt is connected parallel to the galvanometer. Since resistance of shunt is very small: \[ I_s \gg I_g \] where:

• \(I_s\) = current through shunt
• \(I_g\) = current through galvanometer

Thus, most current flows through the shunt wire.

Step 4: Conclusion.
Therefore, to convert a galvanometer into an ammeter, we use: \[ \boxed{\text{Shunt wire in parallel}} \]