[Physics Class Notes] on Difference Between Ammeter and Voltmeter Pdf for Exam

Ammeter and voltmeter both devices are used in an electrical circuit to measure different aspects of electricity. Among them, an ammeter gives you the measure of current while the voltmeter helps in calculating the voltage or potential difference between two points in an electric circuit. 

What is Ammeter and Voltmeter?

Ammeter – It is an instrument that is used to measure the current in an electrical circuit. It gets its name from Ampere which is the unit of electric current. 

Applications of an Ammeter:

• This device is easily available and helps determine the flow of current quite accurately.

• It can be used both domestically and for industrial purposes. 

• It is widely used by manufacturing and instrumentation companies.

• It can be used with a thermocouple to measure temperature.

• It can be used to check faulty circuits in offices and homes. 

Voltmeter – This instrument measures the voltage between two points in an electrical circuit. It is present in both digital and analogue forms. 

Applications of a Voltmeter

• A voltmeter is used for a number of purposes even though it is not as accurate as an ammeter.

• It measures the voltage in a circuit and is also used in both homes and big factories.

• It proves quite useful in debugging thereby certifying the presence of the optimal value of the required voltage.

• It can be coupled with cathode ray tubes to ensure the accuracy of the results and measurements taken. 

• It is also used in labs by young students and scholars for experimenting and testing purposes.

What is the Difference Between Ammeter and Voltmeter? 

There are two ways to measure electricity 

• Using current 

• Using voltage

Ammeter and voltmeter are used to measure the flow of current and the measure of voltage, respectively. The significant difference between these two devices lies in their use. Further, look at the table below to understand the difference between an ammeter and a voltmeter. 

Mentioned above are a few significant differences between ammeter and voltmeter. Both instruments are present in analogue and digital forms. Analogue meters have a pointer that depicts the measurement whereas digital devices display the value of current or voltage on the screen.  

Galvanometer

We have talked about ammeters and voltmeters but now let’s see what a galvanometer is. It is a device used to detect current flow in a circuit. Current sensitivity is the term used to refer to the current that gives a full-scale deflection of the galvanometer’s needle. Thus, it is the maximum current that the instrument is capable of measuring. A galvanometer can even function as an ammeter or a voltmeter upon making some requisite changes. 

Potentiometer

When we try measuring the EMF of a battery, we generally connect the battery directly to a standard voltmeter as in the case in laboratories. However, this implies that the actual quantity measured by the voltmeter is the terminal voltage V. Voltage is related to the EMF of the battery by the equation V=emf−Ir, where the letter i is used to denote the current that flows in the circuit and r is the internal resistance of the battery. 

A potentiometer is a null measurement device that is also used to measure voltage but in a slightly different manner. A voltage source is connected to a resistor in the circuit, and a constant current is made to pass through it. There is a steady drop in potential along with the wire present. Consequently, a variable potential is obtained through contact along the wire.

Multiple-Choice Questions 

1. Current is measured using _______ by connecting it in _______ with the electric circuit. 

1. Voltmeter, series

2. Voltmeter, parallel

3. Ammeter, series

4. Ammeter, parallel

Ans: c 

2. Digital meters are preferred over analogue meters. 

1. True 

2. False 

Ans: a

3. An ideal voltmeter can be considered as a _________ circuit. 

1. Power

2. Infinite 

3. Short

4. Open 

Ans: d 

4. An ideal ammeter can be treated as a __________ circuit. 

1. Open 

2. Short

3. Infinite 

4. Power

Ans: b