Shunt resistance

Definition

Shunt resistance is a low-value resistor connected in parallel with an ammeter to allow most of the current to bypass the meter. It is used to extend the current range of the instrument while keeping the meter movement safe.

5 Must Know Facts For Your Next Test

1. Shunt resistance enables a voltmeter or ammeter to measure higher currents than its normal range.
2. It protects sensitive components in measuring devices by diverting excess current away from them.
3. The value of shunt resistance is carefully chosen based on the desired current range and the internal resistance of the meter.
4. In DC circuits, shunt resistors must have a very low resistance value compared to the meter's internal resistance.
5. The voltage drop across the shunt resistor is proportional to the total current flowing through it, allowing for accurate measurement.

Review Questions

• What role does shunt resistance play in an ammeter?
• How does shunt resistance affect the current measurement in a circuit?
• Why is it important for a shunt resistor to have a low resistance value?

Related terms

Ammeter: An instrument used to measure electric current in a circuit.

Voltmeter: A device used to measure electric potential difference between two points in an electric circuit.

Internal Resistance: The inherent resistance within electrical devices that causes a voltage drop when current flows through it.