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When a current-carrying conductor is placed in a magnetic field, the conductor experiences a force which acts to push the conductor out of the field. This is the principle of operation of an analogue ammeter and voltmeter.

A light coil of wire supporting a pointer is placed between the poles of a permanent magnet. Whenever the coil rotates, the pointer sweeps across an appropriately-calibrated scale. When current flows through the coil, a torque acts to rotate the coil. However, the movement of the coil is restrained by a pair of hairsprings. When the torque due to the current is balanced by the restraining torque of the hairsprings, the coil stops rotating. Thus, the angle through which the coil rotates is proportional to the current flowing through it, and the instrument is calibrated such that the pointer directly indicates that value current on a curved scale.

Ammeters and voltmeters both work on the same principle. In the case of the voltmeter, the current which operates the coil is proportional to the voltage appearing across the instrument. The difference between the two instruments is the way in which resistors are used, within the instruments, to make one suitable for measuring current and the other suitable for measuring voltage.

Ammeters must be connected in series with the circuit under test, whereas voltmeters must be connected in parallelwith the circuit under test.

Digital ammeters and voltmeters work on a completely different principle, using an electronic 'gate' to switch on and to switch off a series of pulses. The time for which the gate is 'open' is a function of the value of the current or voltage being measured -e.g. the larger the current, the longer the gate is held open. These pulses are then counted and, in simple terms, the greater the number of pulses counted, the greater the current or voltage being measured. The output is then presented, directly in amperes or volts, on a LED or LCD screen.

For use in the field, analogue and digital multimetersare available. These allow current, voltage, and resistance to be measured using the same instrument.

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โˆ™ 2011-01-12 08:00:05
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Q: Can you explain how a voltmeter and ammeter work?
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Why do you have specific resistance combination inside a voltmeter and an ammeter Explain?

in voltmeter we have internal Resistance and connected in series , to current don't transfer in voltmeter , and we have internal resistance in ammeter and connected in parallel , to most current transfer through the ammeter.


How ammeter used as voltmeter?

You cannot convert an ammeter into a voltmeter.


What is a ammeter and voltmeter used for?

Ammeter measures current and Voltmeter measures volts


How is ammeter and voltmeter attached to a circuit?

An ammeter is connected in series and a voltmeter is attached in parallel.


To calibrate voltmeter and ammeter using potentiometer?

to calibrate voltmeter and ammeter using potentiometer


What would happen when the ammeter is placed in parallel and the voltmeter in series with the circuit at the same time?

If the voltmeter was ahead of the ammeter, the voltmeter would read supply voltage, and the ammeter would read current through the voltmeter, a very small reading. If the ammeter was ahead of the voltmeter, the ammeter would read supply current, which is probably many times in excess of the ammeter's rating, so you would either destroy the ammeter (or battery) or blow its fuse. It does not matter about the voltmeter, as the ammeter is now blown.


How is an ammeter converted to a voltmeter?

An ammeter can be converted into a voltmeter by connecting a resistor in series with it. This works best if the ammeter is a very sensitive ammeter, such as in the micro ampere range. More commonly, a voltmeter (or sensitive ammeter) is converted into an ammeter by placing a small resistor in parallel with it.


How would you connect an ammeter and a voltmeter in a circuit?

Connect ammeter in series and voltmeter in parallel to the circuit


Resistance and power measurement using voltmeter-ammeter method?

What is the definition of voltmeter-ammeter method?


How do you connect an ammeter and voltmeter?

The voltmeter is connected across the supply and the ammeter is connected in series with the supply.


How does an ammeter work?

An ammeter is a low voltage voltmeter in parallel with a small resistance resistor. Current flow through the resistor creates a voltage drop across it which is then measured by the voltmeter.


How does ammeter work?

An ammeter is a low voltage voltmeter in parallel with a small resistance resistor. Current flow through the resistor creates a voltage drop across it which is then measured by the voltmeter.


How can you say that ammeter measures current and voltmeter measures voltage?

voltmeter in parallel and ammeter in series of a circuit.


How do you connect voltmeter and ammeter in the circuits?

the voltmeter is connected across the supply and the ammeter is connected in series with the supply


Voltmeter in series?

No. Voltmeter in parallel. Ammeter in series.


Where ammeter and voltmeter are put in circuit?

the ammeter is put in series in the circuit ... and the voltmeter in parallel with what's you're measuring


What will happen if ammeter and voltmeter interchanged?

The ammeter would be destroyed by excessive current but nothing would happen to the voltmeter


Difference between ammeter and voltmeter?

The difference is that the voltmeter is a lulu


What is the value of resistance when voltmeter and ammeter are ideal?

An ideal voltmeter has infinite resistance, while an ideal ammeter has zero resistance.


What will happen when ammeter is connected in parallel and voltmeter is connected in series?

An ammeter has a very low resistance, and a voltmeter has a very high resistance. So the ammeter will short circuit the supply, while the voltmeter will significantly increase the resistance of the load.


How is voltmeter connected to ammeter?

in series


Calibration of ammeter for application of voltmeter?

An ammeter should not be used as a voltmeter. An ammeter is a low impedance device that measures the current going through a circuit, often by measuring the small voltage across a known resistance. A voltmeter is a high impedance device that measures the voltage across a circuit. If you were to connect an ammeter as if it were a voltmeter, you would effectively short out the circuit, drastically affecting its operation, and potentially damaging both the circuit and the ammeter.


What do you mean by calibration of ammeter and voltmeter?

to check the accuracy of voltmeter with the help of potentiometer


What will happen to the current in a circuit if a voltmeter is mistaken for ammeter?

Voltmeter must be connected parallel and ammeter in series, if voltmeter is connected in series, only the voltage of the source will be read, and the current is approx. zero because voltmeter is a high resistance tester.


What will happen when ammeter and voltmeter positions are interchanged?

The ammeter will almost certainly blow its fuse.

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