A galvanometer is a device used to detect or measure the small electric current flowing in the circuit.
- It is also known as the moving coil galvanometer.
- It was based on the principle that when a current-carrying loop is placed in a uniform magnetic field, it experiences a torque.
- It consists of a coil that is kept between the two poles of a permanent magnet which is cylindrical in shape in order to provide a radial magnetic field.
- The radial magnetic field produced by cylindrical poles of permanent magnets is always parallel to the plane of the coil.
The following are the uses of a galvanometer
- It is used to detect electric current in the circuit.
- It is converted to an ammeter by connecting a low resistor parallel to it.
- It is converted to a voltmeter by connecting a high resistance in series with it.
- By making special arrangements, it can be used as an ohmmeter.
The figure of merit of the galvanometer is defined as the amount of current producing one scale deflection of the galvanometer. It is given by
Figure of merit = Current / Deflection
An ammeter is an instrument used to measure electric current in an electric circuit. A galvanometer can be converted into an ammeter by connecting a low resistance (called a shunt) parallel to the galvanometer.
A voltmeter is an instrument used to measure the potential difference across the two ends of a circuit element. A galvanometer can be converted into a voltmeter by connecting a high resistance in series to the galvanometer.
Ques. Why a galvanometer is known as the fundamental electrical measuring tool?
Ans. Since a galvanometer is designed to measure voltage and current, therefore it is known as the fundamental electrical measuring tool.
Ques. What is a galvanometer?
Ans. Galvanometer is a device used to measure or detect small electric currents flowing in the circuit.
Ques. Should the galvanometers possess a high or low resistance?
Ans. Galvanometers must have low resistance.
Ques. What is the principle behind a galvanometer?
Ans. A galvanometer is based on the fact that when a current-carrying loop is placed in a uniform magnetic field, it experiences a torque.
Ques. Should voltmeters possess low resistance or high resistance? Why?
Ans. Voltmeters should always have a high resistance; otherwise, the potential difference
being measured will be reduced.
Ques. What is the main procedure to convert a galvanometer into a voltmeter?
Ans. A galvanometer can be converted into a voltmeter by connecting a large resistance in series to the galvanometer.
Ques. What do you mean by a galvanometer’s figure of merit?
Ans. The figure of merit of a galvanometer is the electric current required to produce a one-division deflection in the galvanometer.
Ques. A galvanometer is transformed into a milliammeter and an ammeter. Which of the two devices will have better resistance?
Ans. The Milliammeter will have more resistance.
Ques. What is the resistance value of ideal ammeters?
Ans. The resistance of an ideal ammeter is zero.
Ques. Should ammeters have high or low resistance? Why?
Ans. Ammeters should always have a low resistance; otherwise, they will reduce the current being calculated.
Ques. How are ammeters joined in an electric circuit?
Ans. In an electric circuit to measure the electric current, ammeters are always connected in series.
Ques. What is the resistance value of ideal voltmeters?
Ans. An ideal voltmeter should have infinite resistance.
Ques. What is the main procedure to convert a galvanometer into an ammeter?
Ans. In general, a galvanometer is transformed into an ammeter of a certain range by connecting an appropriate small resistance (shunt) in a parallel configuration with the galvanometer.
Ques. How is a voltmeter joined into an electric circuit?
Ans. In an electric circuit to measure the potential difference, a voltmeter is always connected in parallel.
Ques. Define the sensitivity of a galvanometer.
Ans. A galvanometer is said to be sensitive if a small current flowing through the coil of the galvanometer produces a large deflection in it.
Ques. How many types of sensitivity does a galvanometer have?
Ans. A galvanometer has two types of sensitivity
- Current sensitivity
- Voltage sensitivity
Ques. Define current sensitivity.
Ans. The current sensitivity of a galvanometer is defined as the deflection produced in the galvanometer per unit of current flowing through it.
Ques. Define voltage sensitivity.
Ans. The voltage sensitivity of a galvanometer is defined as the deflection produced in the galvanometer per unit of voltage applied to it.
Ques. How is the deflection of the coil in a galvanometer related to the current flowing through it?
Ans. The deflection of the coil in a galvanometer is directly proportional to the current flowing through it.
Ques. What is an ohmmeter?
Ans. An ohmmeter is an electrical device used to measure electrical resistance. Multimeters also act as ohmmeters in resistance-measuring mode.
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