# A Voltmeter, Ammeter & Cell are Connected in Series. Ammeter shows No Deflection. Why?

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• 4:19 min

• 28 Aug 2024

## A Voltmeter, Ampere Meter and a Battery Cell are connected in Series. It is Observed that Ammeter Practically Shows No Deflection. Why?

Due to the large resistance of the voltmeter, the circuit resistance becomes very high. As a result, very small current will flow in the circuit. This small current passing through the coil of voltmeter will produce some deflection. However, in case of ammeter (Ampere meter), most of this small current will flow through the shunt. Consequently the deflection of the ammeter will be practically nil.

The shunt resistor (a parallel resistance with the ammeter) is used to protect the meter when high current passes through the ampere meter coils. In case of high current, the major part of current passes through the shunt and the voltage drops occurs across it which still not affect the main function of ammeter i.e. moment remains same but protects the meter from damaging the internal coils.

In the above case, the current select a way having lowest resistance. So it passes through the shunt resistor or ammeter. That’s why there is no deflection in ampere meter when connected in series with battery and voltmeter in series.

In short, ammeters are designed to measure low currents but in case of high currents, a major portion of the measuring current passes through the shunt resistance which is connected in parallel with ammeter and swamping resistance (the swamping resistance protect the meter from high temperature). Thus, it wont affect the measuring ability of ampere meter but provide protection against burning the meter. Shunt resistor has lower value than the internal resistance of ammeter, that’s why high currents pass through it due to lowest compared resistance.

## FAQ

### What happens when ammeter and voltmeter are connected in series?

Solution: A voltmeter is a high resistance (infinite in the ideal case) device. If connected in series with the load the overall resistance of the circuit will become very high (infinite in the ideal voltmeter case). Due to this high resistance, the current flowing in the circuit will tend to zero i.e. become very low

### Are a cell an ammeter and a voltmeter all connected in series?

A cell, an ammeter and a voltmeter are all connected in series. The ammeter reads a current I and the voltmeter a potential difference V. If a torch bulb is connected across the voltmeter, then. An ammeter and a voltmeter are connected in series to a battery with an emf ε=6.0 V

### Why ammeter is not connected in parallel and voltmeter is not connected in series?

Conclusion: – In summary, an ammeter is connected in series to measure current accurately without altering the circuit’s resistance, while a voltmeter is connected in parallel to measure voltage without affecting the current flow

### Why ammeter is connected in series and it has low resistance?

A Ammeter is used to measure the current flowing through a component/circuit. Since, current remains same in series connection and also the resistance of an ammeter is very small due to which it doesn’t affect the current to be measured. So, an ammeter is connected in series to measure current

### Why can’t a voltmeter be connected in series?

A Voltmeter has very high resistance to ensure that it’s connection do not alter flow of current in the circuit. Now if it is connected in series then no current will be there in the circuit due to it’s high resistance. Hence it is connected in parallel to the load across which potential difference is to be measured

### Why is the voltmeter always connected in parallel?

An ideal voltmeter has high resistance, because It is a high resistance device, so it is connected in parallel combination, so as to minimize the resultant resistance. It minimizes the current through voltmeter such that it will measure accurate voltage between two points

### Are an ammeter and A voltmeter initially connected in series?

An ammeter and a voltmeter are connected in series to a battery of emf 6V. When a certain resistance is connected in parallel with the voltmeter, the reading of the latter decreases n = 2 times, whereas the reading of the ammeter increases the same number of times

### Should A voltmeter be connected in series or parallel?

Voltmeters are connected in parallel with whatever device’s voltage is to be measured. A parallel connection is used because objects in parallel experience the same potential difference

### Why a voltmeter is connected in parallel and an ammeter in series of a circuit component to calculate the desired value?

Ideal voltmeter has infinite resistance so no current will flow. This is why voltmeters are placed in parallel to the circuit, not in series. Ammeter is placed in series however and has low resistance

### Why must an ammeter never be connected in parallel across a battery?

When ammeter is connected in parallel to the circuit, net resistance of the circuit decreases. Hence more current is drawn from the battery, which damages the ammeter

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