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How are the figure of merit and current sensitivity of galvanometer related with each other?

Author

Eleanor Gray

Published Mar 04, 2026

How are the figure of merit and current sensitivity of galvanometer related with each other?

The resistance of the coil of the galvanometer is called the resistance of the galvanometer. Figure of merit of a galvanometer is the reciprocal of current sensitivity. Galvanometer deflection is proportional to the amount of current passed through it.

Besides, what is the figure of merit of a galvanometer?

Figure of Merit is essentially the “full scale deflection current (FSD) divided by the number of graduations on the meter's scale. It is also the reciprocal of the “sensitivity” of the meter that is measured in Ohms per Volt times the number of graduations on the meter's scale.

Also, what is current sensitivity? Current sensitivity is the measure of responsiveness of any instrument to the change of current through it. Voltage sensitivity is the measure of responsiveness of any instrument to the change of applied voltage across it.

Also asked, what is current sensitivity of ballistic galvanometer?

The charge sensitivity of a ballistic galvanometer may be defined as the (transient) charge needed to have a unit value for the first maxima of the deflection of its coil. 2.0. 5 votes.

How can a galvanometer be made more sensitive?

To sum up, the sensitivity of Moving Coil Galvanometer increases by: of turns and the area of the coil, Increasing the magnetic induction and. Decreasing the couple per unit twist of the suspension fibre.

Why we use half deflection method?

Half deflection is a very wise way of finding the galvanometer resistance. Ammeter introduce it's own resistance in the circuit causing the current to reduce, and voltmeter will reduces the effective resistance causing voltage to reduce. This is why ideally we need Ammeter with resistance and Voltmeter with resistance.

How is figure of merit calculated?

Figure of merit of the galvanometer :
Record the observations in a tabular column. Repeat the experiment by changing the value of R and note the galvanometer deflection each time. We can find the figure of merit of the galvanometer by using the equation, k= E/(R+G)θ.

What is the principle of galvanometer?

Galvanometer works on the principle of conversion of electrical energy into mechanical energy. When a current flows in a magnetic field, it experiences a magnetic torque. If it is free to rotate under a controlling torque, it rotates through an angle proportional to the current flowing through it.

What is half deflection method?

The half deflection method is the method by which an internal resistance of a cell can help in evaluating value which is considered as high.

What is the use of figure of merit?

A figure of merit is a quantity used to characterize the performance of a device, system or method, relative to its alternatives. In engineering, figures of merit are often defined for particular materials or devices in order to determine their relative utility for an application.

How can we convert galvanometer into ammeter?

A galvanometer can be converted into ammeter by connecting a low resistance called shunt in parallel to the galvanometer. A voltmeter is a device used to measure the potential difference between two points in a circuit.

What is half deflection method in galvanometer?

A method of finding the internal resistance of a cell when the value is known to be high. A second cell, a galvanometer and a resistance are connected in series with the cell under test, and the value of the resistance required to give a galvanometer. deflection of half the value obtained with the cell alone is found.

What do you mean by figure of merit?

Definition of figure of merit. : a numerical quantity based on one or more characteristics of a system or device that represents a measure of efficiency or effectiveness.

What is sensitivity of galvanometer?

Thus current through the coil is directly proportional to the angle of twist of the suspension (or deflection) q. SENSITIVITY OF GALVANOMETER. Sensitivity of galvanometer is defined as the current in micro ampere required to consume one millimeter deflection on a scale placed 1m away from the mirror.

What is the unit of current sensitivity?

Current sensitivity is defined as the ratio of deflection produced in the galvanometer to the current flowing through it. SI unit is radian per ampere.

On what factors sensitivity of galvanometer depends?

State two factors on which the sensitivity of a moving coil galvanometer depends. The sensitivity of a moving coil galvanometer depends upon: (a) The value of n, i.e., number of turns. (b) The value of B, i.e., intensity of magnetic field.

Why should we use a sensitive galvanometer?

Sensitivity of galvanometer is defined as the current in microamperes required for 1mm deflection on a scale placed 1 metre away from the mirror. You do not have any other instrument so sensitive, and galvanometer is used in precision measurement in science experiments.

What is ballistic constant?

: a constant in ballistics that represents the efficiency of a projectile in overcoming air resistance.

How many types of galvanometer are there?

Moving-coil galvanometers are mainly divided into two types: Suspended coil galvanometer. Pivoted-coil or Weston galvanometer.

What is the relation between the sensitivity and deflection for a galvanometer?

The deflection of a galvanometer per unit current is called current sensitivity of galvanometer. So, current sensitivity of a galvanometer can be increased by increasing the value of B, N and A. It can be decreased by decreasing the value of k.

What is the difference between galvanometer and ballistic galvanometer?

What is the difference between ballistic galvanometer and simple galvanometer? A conventional galvanometer has as low a mass as possible in the moving coil. A Ballistic galvanometer has an artificially increased mass. It is essentially a combination of a moving coil and a mechanical integrator.

What are conditions for galvanometer to be ballistic?

The conditions are : the moving coil must be wound on a metallic frame and eddy currents must be produced during needle oscillation. What happens when a galvanometer is connected with a shunt? Earlier, it was detecting the presence or direction of the current, & now, it starts measuring the amount of the current.

What is sensitivity of multimeter?

The resistance offered per volt of full scale deflection by the multimeter is known as multimeter sensitivity. it indicates the internal resistance of the multimeter. If the sensitivity of a multimeter is high, it means that it has high internal resistance.

How can we increase the current sensitivity of a galvanometer?

Current sensitivity can be increased by increasing the number of turns of the coil. However, this increases the resistance of the coil also(R is proportional to length of conductor).

What is voltmeter sensitivity?

voltmeter sensitivity. [′vōlt‚mēd·?r ‚sen·s?′tiv·?d·ē] (electricity) Ratio of the total resistance of the voltmeter to its full scale reading in volts, expressed in ohms per volt.

What is charge sensitivity?

Charge sensitivity is the charge generated in the PZT for every 'g' of input acceleration. The unit for charge sensitivity is pF/ g.

How galvanometer is converted into ammeter and voltmeter?

A galvanometer can be converted into voltmeter by connecting a high resistance called multiplier in series to the galvanometer. This equation gives the value of resistance R, which connected in series to the galvanometer, is converted into a voltmeter of range 0 – V volts.

How is voltage sensitivity calculated?

Current sensitivity, σi=Iθ, where θ is the deflection produced. But V=IR=IG as given Gis the resistance of the galvanometer. The above relation implies that if current sensitivity increases as well as the resistance increases in same order, the voltage sensitivity will remain unchanged.

What do you mean by current sensitivity of a moving coil galvanometer?

The sensitivity of a Moving Coil Galvanometer is defined as the ratio of the change in deflection of the galvanometer to the change in current. Therefore we write, Sensitivity = dθ/di. If a galvanometer gives a larger deflection for a small current it is said to be sensitive.

Can a galvanometer be used to measure current?

NO. A galvanometer is a device which is only used to detect the presence of current in a circuit. The deflection in the galvanometer gives the direction of flow of current i.e. if the deflection is towards right, current is flowing in the right direction and vice versa. An ammeter is used for measuring current.

Why does the galvanometer deflect in the opposite direction?

it is due to the magnetic effect of electric current. when current is passed through the wires the magnetic field is produced and this magnetic field is linked with galvanometer. thus galvanometer deflects in opposite direction.

Why galvanometer is not used in AC Bridge?

Galvanometer only detects the flow of direct current because it's an unidirectional. But in case of alternating current, it's sinusoidal i.e. For positive half, it travels in a direction and in negative half, it travels in the opposite direction. This cancels each other in a cycle. Hence, no deflection in Galvanometer.

Why does the galvanometer deflect?

Inside the galvanometer there is a permanent magnet and an electromagnet and when the magnetic field is produced inside the coil is in opposite nature to the nature of magnetic field of permanent magnet the needle deflects and when the nature of magnetic field become same of each others then also needle deflects .

Who invented galvanometer?

Johann Schweigger

Why shunt is connected in parallel to galvanometer?

Since Galvanometer is a very sensitive instrument therefore it can't measure heavy currents. In order to convert a Galvanometer into an Ammeter, a very low resistance known as "shunt" resistance is connected in parallel to Galvanometer. Value of shunt is so adjusted that most of the current passes through the shunt.

Why galvanometer is not used to measure current?

A galvanometer cannot be used as such to measure current due to following two reasons : A galvanometer has a finite large resistance and is connected in series in the circuit, so it will increase the resistance of circuit and hence charge the value of current in the circuit.

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