Introduction

The correct method of connecting a voltmeter is by placing it in parallel with the component or section of the circuit where the voltage measurement is required. However, it is important to understand the implications of connecting a voltmeter in series. This article aims to provide a detailed explanation of the issues that arise with series connections and how it affects the circuit and measurements.

High Internal Resistance

Firstly, we need to consider the internal resistance of the voltmeter. Voltmeters are designed with a very high internal resistance to minimize their impact on the circuit they are measuring. When connected in series, the voltmeter acts as an additional resistor, significantly increasing the overall resistance of the circuit. This resistance can lead to a substantial reduction in current flow, potentially resulting in an open circuit if the current drops to zero.

Current Flow and Circuit Function

Connecting a voltmeter in series effectively reduces the circuit's current flow. Since the voltmeter restricts the current passing through the circuit, it may not allow any current to pass through, leading to a complete shutdown of the circuit. This can happen if the voltmeter's internal resistance is too high, causing the current to drop to a level where the circuit no longer functions as intended.

What Happens When Voltmeters are Connected in Series?

When more than one voltmeter is connected in series, the voltage readings are divided across the voltmeters. If the voltmeters have equal resistance, each will display half of the total voltage if only two are used. With four voltmeters, each would read a quarter of the total voltage. This is due to the fact that the voltage is distributed among the resistances in the series connection, leading to incorrect voltage measurements.

Potential Damage

Connecting a voltmeter in series can also lead to potential damage to the meter or the circuit. The increased resistance can cause excessive voltage across the voltmeter, which may exceed its rating and damage its internal components. Voltmeters are meant to measure the voltage across a specific section of the circuit without disrupting it, and connecting them in series can disrupt this balance.

Conclusion

In summary, a voltmeter should always be connected in parallel with the component or section of the circuit where the voltage is to be measured. Connecting it in series will result in incorrect measurements and may damage the voltmeter or the circuit. It is crucial to follow the correct measurement techniques to ensure accurate readings and to protect your equipment.

Final Notes on Series vs Parallel Connections

For measuring very small currents, it might be necessary to use voltmeters in series. For instance, using a voltmeter with extremely high resistance, such as a 20,000 ohms/volt meter, in series can help measure very small currents like 50 microamps. Similarly, multimeters with high input resistance can also be used in series to measure minute currents. However, these applications are the exception and not the rule.

It is important to note that connecting ammeters in series can still provide valid current measurements if the ammeters used have similar resistance. Voltmeters, on the other hand, will give incorrect readings if connected in series due to their high internal resistance. Therefore, it is essential to always use voltmeters in parallel for accurate voltage measurements.