An ammeter is always connected in series (it has a very small internal resistance), and a voltmeter is always connected in parallel (it has a very large internal resistance). Assume that the resistance of an ammeter is 1 mV and the resistance of a voltmeter is 10 kV.
The Correct Answer and Explanation is :
In electrical circuits, ammeters and voltmeters are designed to measure current and voltage, respectively, and are connected in specific ways to ensure accurate readings. The way these devices are connected to the circuit plays a critical role in their functionality, and the resistance of each instrument directly influences the measurement process.
- Ammeter Connection and Resistance:
An ammeter is always connected in series with the circuit because it measures the current flowing through the circuit. For accurate current measurement, the ammeter needs to be placed in the path of the current flow. An important feature of an ammeter is that it has a very small internal resistance (1 milliohm or 1 mV). This low resistance ensures that the ammeter does not significantly alter the current flowing in the circuit, which would lead to incorrect readings. If an ammeter had a high resistance, it would reduce the current, thus distorting the measurement. - Voltmeter Connection and Resistance:
A voltmeter, on the other hand, is always connected in parallel with the component across which the voltage is being measured. This is because a voltmeter is designed to measure the potential difference (voltage) between two points in the circuit. To avoid drawing any significant current through itself, which would affect the voltage being measured, the voltmeter has a very high internal resistance (10 kV in this case). The high resistance ensures that the voltmeter draws minimal current, preventing any significant change in the voltage across the component being measured. If a voltmeter had a low resistance, it would shunt current from the circuit, altering the voltage and leading to incorrect readings.
In conclusion, the design and resistance characteristics of ammeters and voltmeters are crucial to ensuring accurate measurements. The ammeter’s small resistance allows it to measure current without significantly affecting the circuit, while the voltmeter’s large resistance ensures it measures voltage without drawing substantial current and altering the circuit’s behavior.
