Difference Between Ammeter and Galvanometer

Edited By Vishal kumar | Updated on Jul 02, 2025 04:46 PM IST

The article includes answers for what is ammeter, the function of ammeter, use of ammeter, galvanometer, use of a galvanometer, and the difference between galvanometer and ammeter, the difference between galvanometer and voltmeter, and the difference between galvanometer and ohmmeter etc.

Note: Ammeter in Hindi means ऐमीटर, ammeter meaning in Tamil is அம்மீட்டர், conversion of galvanometer into ammeter in Hindi is धारामापी से अमीटर बनाना

What is the function of an ammeter?

A device measuring the electric current in a circuit is called an ammeter. The SI unit of current is ampere. As the device measures current in ampere, it is named an ammeter. The main function of the ammeter is to measure direct or indirect electric current.

Also read -

JEE Main/NEET 2027: Physics Important Formulas for Class 10

NEET 2025: Mock Test Series | Syllabus | High Scoring Topics | PYQs

JEE Main: Study Materials | High Scoring Topics | Preparation Guide

JEE Main: Syllabus | Sample Papers | Mock Tests | PYQs

Difference Between Ammeter and Galvanometer

How does ammeter work?

The ammeter measures the electric current through a set of coils with a low value of resistance and inductive reactance. An ammeter is designed with the principle that the resistance and inductive reactance should have a low value. To have the same current throughout, the circuit connection in the ammeter should be in series.

Types of ammeter:

Ammeter is classified into the following types depending on the constructing principle.

The permanent magnet moving coil ammeter: In this type, the ammeter is kept in the middle of the pole of a permanent magnet. Here, the magnitude of the current doesn’t affect the deflection in the coil. Direct current is measured by this ammeter.
Rectifier type ammeter: Alternating current is measured by this type of ammeter.
Moving iron ammeter: Current passing through the coil affects the deflection of the coil. Both direct and alternating current is measured by this ammeter.
Electrodynamometer type ammeter: It is more accurate than other types of ammeter. It also measures both the currents.

Depending on the current measurement, the ammeter is divided into further two types. They are AC ammeter and DC ammeter.

What is the use of an ammeter?

Ammeter is used in many sectors.

To check the circuit problems, electricians use an ammeter.
It is used to examine the temperature in a thermocouple.
It measures the electric current produced by the circuit.
The proper functioning of electronic devices is checked by an ammeter.

Related Topics Link,

What is a galvanometer?

A device that measures small electric current produced by the deflection of a moving coil is called a galvanometer.

What does a galvanometer do?

The magnetic effect of electric current is the working principle of the galvanometer. A deflection is observed in the galvanometer’s needle if there is a current in the circuit.

Types of galvanometer:

Types of galvanometer comprise:

Tangent galvanometer
Mirror galvanometer
Ballistic galvanometer
Astatic galvanometer

What is the reduction factor of the tangent galvanometer?

To generate a specific deflection, the amount of current needed to pass through the galvanometer is called the reduction factor of the tangent galvanometer.

What is the use of a galvanometer?

The galvanometer is used in the following examples:

Laser TV, laser displays, laser engraving, etc use galvanometers to manage their systems.
The galvanometer is used to measure the condition of hard drives and CD players.

What is the difference between an ammeter and a galvanometer?

Although both the ammeter and galvanometer measure electric current, they have difference between them. They are,

Ammeter	Galvanometer
An electric device that measures the current is called an ammeter.	A mechanical device that measures the current is called a galvanometer.
In an ammeter, only the magnitude of the current is measured.	Both the magnitude and direction of the current are measured by the galvanometer.
Ammeter detects both direct and alternating currents.	Galvanometer detects only direct current.
For an ammeter, the magnetic field is not required.	The functioning of a galvanometer requires a magnetic field.
Ammeter is connected in series with the circuit directly.	Using the potentiometer, the galvanometer measures current.
Ammeter is less sensitive.	A galvanometer is more sensitive.
Ammeter is more accurate.	A galvanometer is less accurate.

Read Also :

NEET Highest Scoring Chapters & Topics

This ebook serves as a valuable study guide for NEET exams, specifically designed to assist students in light of recent changes and the removal of certain topics from the NEET exam.

Download E-book

What is a voltmeter?

In an electric circuit, an instrument calculating the electrical potential difference between two ends is called a voltmeter. It measures voltages in volts. The potential difference of either direct or indirect current is measured by the device.

Types of voltmeter:

Types of voltmeters based on the construction principle are,

The permanent magnet moving coil voltmeter
Rectifier type voltmeter
Induction type voltmeter
Electrostatic type voltmeter
Electro dynamometer voltmeter
Digital voltmeter

What is an Ohmmeter?

A device that is used to measure electrical resistance is called an ohmmeter. As the resistances are measured in ohm units, the instrument is known as an ohmmeter. Ohmmeter circuit can be either parallel or series.

The Ohmmeter consists of a needle, and two test leads. The battery controls the deflection in the needle. At first, the two test leads should be shorted and the resistance value is noted. Then a fixed range is set for the device. The current will be highest when the needle reaches the highest point on the meter scale. Test leads are removed after testing the circuit. Once when the test leads are connected again, the battery is discharged. The rheostat is adjusted when the leads are shorted. Then the test leads will have zero resistance as the needle reaches the lowest position, zero.

NCERT Physics Notes :

Types of Ohmmeter:

Depending on the application, Ohmmeter is divided into three types. They are,

Series type Ohmmeter
Shunt type Ohmmeter
Multiple type Ohmmeter

Application of ohmmeter:

The ohmmeter is applicable in the following fields:

To test the electronic component, an ohmmeter is used in electronic labs.
The ohmmeter is used to verify the circuit's functioning.
For debugging, it is used in small IC’s.

Difference between galvanometer and voltmeter:

Galvanometer and voltmeter differ as follows:

A galvanometer measures the current in the circuit while a voltmeter is a device that calculates the electrical potential difference between two ends in a circuit.
The direction of current is measured by the galvanometer but the voltmeter doesn’t measure the current only.
The functioning of a galvanometer requires a magnetic field whereas a voltmeter doesn’t require a magnetic field.
The circuit connection is in series in the case of the galvanometer while it is parallel in the case of the voltmeter.

Difference between galvanometer and ohmmeter:

The difference between galvanometer and ohmmeter are,

The galvanometer measures the electric current in the circuit and the ohmmeter measures the electrical resistance.
In galvanometer circuit is in series while the ohmmeter circuit is either series or parallel.

Also check-

Frequently Asked Questions (FAQs)

1. Which has greater resistance milliammeter or ammeter?

Milliammeter has greater resistance than an ammeter.

2. Why do we use a galvanometer?

To detect small currents we use a galvanometer.

3. The galvanometer is connected in series or parallel?

The galvanometer is connected in series.

4. What is the main difference between an ammeter and a galvanometer?

The main difference is their purpose and sensitivity. An ammeter is designed to measure electric current in a circuit, while a galvanometer is a more sensitive instrument used to detect and measure very small electric currents. Ammeters are typically used in practical applications, while galvanometers are often used in laboratory settings for precise measurements.

5. How does the construction of an ammeter differ from a galvanometer?

While both use similar principles, an ammeter is designed to handle larger currents. It typically has a thicker wire in its coil and a stronger spring to counteract the magnetic force. A galvanometer, being more sensitive, uses a thinner wire and a weaker spring to detect smaller currents.

6. Can a galvanometer be used as an ammeter?

Yes, a galvanometer can be converted into an ammeter by adding a low-resistance shunt in parallel with it. This allows the galvanometer to measure larger currents by diverting most of the current through the shunt, while only a small fraction passes through the galvanometer coil.

7. What is the working principle of a galvanometer?

A galvanometer works on the principle of electromagnetic induction. When current flows through its coil, it creates a magnetic field that interacts with a permanent magnet. This interaction causes a deflection of the coil, which is proportional to the current flowing through it. The deflection is indicated by a pointer on a scale.

8. How is an ammeter connected in a circuit?

An ammeter is always connected in series with the component through which the current is to be measured. This ensures that all the current flowing through that part of the circuit passes through the ammeter.

9. Why does an ammeter have low resistance?

An ammeter has low resistance to minimize its impact on the circuit being measured. If an ammeter had high resistance, it would significantly reduce the current flowing through the circuit, leading to inaccurate measurements. The low resistance ensures that the ammeter doesn't alter the circuit's behavior.

10. What is the role of a shunt in an ammeter?

A shunt is a low-resistance conductor connected in parallel with the ammeter's coil. It allows most of the current to bypass the sensitive galvanometer mechanism, enabling the ammeter to measure much larger currents than the basic galvanometer could handle alone.

11. How does temperature affect the readings of ammeters and galvanometers?

Temperature changes can affect the resistance of the coil and the strength of the springs in both devices. This can lead to inaccurate readings. High-quality instruments often include temperature compensation mechanisms to minimize these effects.

12. Why can't a galvanometer measure large currents directly?

A galvanometer is designed to measure very small currents, typically in the microampere or milliampere range. Large currents would generate too much force on the galvanometer's coil, potentially damaging it or causing the pointer to go off-scale.

13. Can a galvanometer detect AC currents?

A standard moving-coil galvanometer can only detect DC currents. For AC currents, specialized instruments like hot-wire galvanometers or rectifier-type instruments are used. These can respond to the average value of alternating currents.

14. What is a "dead-beat" galvanometer?

A dead-beat galvanometer is designed to quickly come to rest at its final position without oscillating. This is achieved by using damping mechanisms, such as air vanes or electromagnetic damping, which reduce oscillations and allow for faster, more accurate readings.

15. What is meant by the "critical damping" of a galvanometer?

Critical damping refers to the condition where the galvanometer's pointer reaches its final position in the shortest time without oscillating. This is achieved by carefully balancing the damping forces, allowing for quick and accurate readings.

16. What is the difference between a moving-coil and a moving-magnet galvanometer?

In a moving-coil galvanometer, the coil moves in a fixed magnetic field. In a moving-magnet type, the magnet moves relative to a fixed coil. Moving-coil types are more common due to their higher precision and lower inertia.

17. How does the moment of inertia of the moving parts affect galvanometer performance?

A lower moment of inertia of the moving parts (coil, pointer) allows for faster response to changes in current. This is important for accurate measurements of rapidly changing currents.

18. What is the purpose of "taut-band suspension" in some galvanometers?

Taut-band suspension replaces pivot bearings with a thin metal band, reducing friction and wear. This increases sensitivity and longevity of the instrument, especially for very small current measurements.

19. What is the role of Coulomb damping in galvanometers?

Coulomb damping, caused by air resistance on the moving parts, helps reduce oscillations in the galvanometer's pointer. This aids in achieving a stable reading more quickly.

20. What is meant by the "ballistic" use of a galvanometer?

Ballistic use refers to measuring the total charge in a short pulse of current. The galvanometer's initial swing is proportional to the total charge, allowing measurement of brief current pulses or capacitor discharges.

21. How does electromagnetic damping work in a galvanometer?

Electromagnetic damping occurs when the moving coil induces eddy currents in nearby conducting materials. These currents create a force opposing the coil's motion, reducing oscillations and improving settling time.

22. How does the "periodic time" of a galvanometer affect its usefulness?

The periodic time is the natural oscillation period of the galvanometer's moving system. A shorter periodic time allows for faster measurements, but may reduce sensitivity. It's a key factor in the instrument's dynamic response.

23. What is the principle behind using a galvanometer as a fluxmeter?

When used as a fluxmeter, the galvanometer measures the total magnetic flux change by integrating the induced voltage over time. This is based on Faraday's law of electromagnetic induction.

24. How does the concept of "critical resistance" apply to galvanometers?

The critical resistance is the external resistance that causes critical damping in the galvanometer. It's important for achieving the optimal balance between quick response and stability in readings.

25. What is the role of "magnetic shielding" in precision galvanometers?

Magnetic shielding protects the galvanometer from external magnetic fields that could interfere with its operation. This is crucial for maintaining accuracy, especially when measuring very small currents.

26. How does the "torque-weight ratio" affect the design of sensitive galvanometers?

A higher torque-weight ratio allows for greater sensitivity. It's achieved by maximizing the magnetic field strength and number of coil turns while minimizing the weight of moving parts. This allows smaller currents to produce measurable deflections.

27. What is the principle behind a "vibration galvanometer"?

A vibration galvanometer is designed to resonate at a specific frequency of alternating current. It's used to detect the presence of AC at that frequency, often in bridge circuits for precise measurements.

28. How does the "self-inductance" of the coil affect galvanometer performance?

The self-inductance of the coil can cause a delay in response to rapid current changes. In DC measurements, this is usually negligible, but it becomes important in AC applications or when measuring rapidly changing currents.

29. What is the principle behind using a galvanometer as a ballistic galvanometer?

A ballistic galvanometer measures the total charge passing through it, rather than steady current. It's designed to have a long period of oscillation, allowing the total deflection to be proportional to the total charge, useful for measuring capacitor discharges or magnetic flux changes.

30. What is the significance of the "figure of merit" in a galvanometer?

The figure of merit of a galvanometer is the current required to produce a unit deflection (usually 1 mm or 1 degree) on the scale. It indicates the sensitivity of the galvanometer - a lower figure of merit means higher sensitivity.

31. How does the sensitivity of a galvanometer compare to that of an ammeter?

A galvanometer is generally much more sensitive than an ammeter. While a typical ammeter might measure currents in the range of milliamperes to amperes, a galvanometer can detect currents as small as microamperes or even nanoamperes.

32. How does the coil design affect the performance of ammeters and galvanometers?

The coil design affects sensitivity and range. Galvanometers typically use many turns of fine wire for high sensitivity to small currents. Ammeters use fewer turns of thicker wire to handle larger currents while maintaining low resistance.

33. What is the importance of "zero adjustment" in galvanometers and ammeters?

Zero adjustment ensures that the pointer indicates zero when no current is flowing. This is crucial for accurate measurements, as it establishes the baseline from which all readings are taken.

34. How do digital ammeters differ from analog ammeters in their working principle?

Digital ammeters convert current to voltage, then use an analog-to-digital converter to display the reading numerically. Analog ammeters rely on the mechanical deflection of a pointer due to electromagnetic forces.

35. Can a galvanometer measure voltage?

A galvanometer itself measures current, not voltage. However, by adding a high-resistance series resistor, it can be converted into a voltmeter, as the current through this high-resistance circuit will be proportional to the voltage.

36. What is the significance of "multiplying power" in ammeters?

Multiplying power is the factor by which the range of an ammeter can be increased by using a shunt. It allows the ammeter to measure currents much larger than its basic full-scale deflection current.

37. How does the magnetic field strength affect the sensitivity of a galvanometer?

A stronger magnetic field increases the torque on the coil for a given current, making the galvanometer more sensitive. However, this must be balanced with other factors like spring stiffness to achieve the desired performance.

38. What is meant by the "swamping resistor" in an ammeter?

A swamping resistor is a temperature-insensitive resistor added in series with the meter movement to minimize the effects of temperature changes on the meter's accuracy.

39. How does the spring constant affect the behavior of a galvanometer?

The spring constant determines the restoring force on the coil. A weaker spring allows for greater deflection with smaller currents, increasing sensitivity, but may also increase oscillation and settling time.

40. How does the resistance of an ammeter affect the circuit it's measuring?

The resistance of an ammeter, though low, still affects the circuit by slightly reducing the current. This effect, called "ammeter insertion loss," is minimized by keeping the ammeter's resistance as low as possible.

41. What is the principle behind a "tangent galvanometer"?

A tangent galvanometer uses a large circular coil and a small compass needle at its center. The tangent of the angle of deflection of the needle is proportional to the current in the coil, hence the name.

42. How do ammeters achieve different measurement ranges?

Ammeters achieve different ranges by using interchangeable shunts or by having multiple shunts that can be selected with a switch. This allows a single meter movement to measure a wide range of currents.

43. How does the shape of the pole pieces affect the performance of a moving-coil galvanometer?

The pole pieces are typically shaped to create a radial magnetic field. This ensures that the torque on the coil is proportional to the current regardless of the coil's position, leading to a linear scale.

44. What is the significance of the "current sensitivity" of a galvanometer?

Current sensitivity is the amount of deflection produced by a unit current. Higher sensitivity allows detection of smaller currents but may also make the instrument more susceptible to disturbances.

45. How do ammeters handle AC measurements differently from DC?

AC ammeters often use rectifiers to convert AC to DC before measurement, or they may use mechanisms that respond to the RMS (Root Mean Square) value of the AC. This is different from DC ammeters which directly measure the steady current.

46. What is the purpose of a "light-beam galvanometer"?

A light-beam galvanometer uses a mirror attached to the moving coil to reflect a beam of light onto a scale. This amplifies small movements, greatly increasing sensitivity and allowing for precise readings of very small currents.

47. How does the "control torque" in a galvanometer affect its operation?

The control torque, usually provided by springs, opposes the deflection caused by the current. It ensures that the deflection is proportional to the current and that the pointer returns to zero when no current flows.

48. What is the difference between a "null" galvanometer and a deflection galvanometer?

A null galvanometer is used to indicate a zero current condition, often in bridge circuits. A deflection galvanometer measures current by the amount of pointer movement. Null types are often more sensitive but don't provide quantitative measurements directly.

49. How does the "figure of merit" of a galvanometer relate to its use as an ammeter?

The figure of merit (current sensitivity) determines the shunt resistance needed to convert a galvanometer into an ammeter of a specific range. A more sensitive galvanometer (lower figure of merit) allows for a wider range of ammeter scales with the same basic movement.

50. What is the significance of the "voltage drop" across an ammeter?

The voltage drop across an ammeter should be as small as possible to minimize its impact on the circuit being measured. A large voltage drop would alter the current in the circuit, leading to inaccurate measurements.

51. What is the significance of "Ayrton shunts" in extending ammeter ranges?

Ayrton shunts are a system of resistors that allow an ammeter's range to be changed without disconnecting it from the circuit. This provides convenience and safety when measuring different current ranges.

52. How does the "angle of swing" method differ from normal galvanometer use?

The angle of swing method uses the maximum deflection of the galvanometer's first swing to measure brief pulses of current or charge. It's useful for measuring capacitor discharges or other transient currents that are too brief for steady-state readings.

53. How does the "frequency response" of a galvanometer affect its use in AC measurements?

The frequency response determines how accurately the galvanometer can measure alternating currents of different frequencies. Most moving-coil galvanometers have limited high-frequency response due to inertia and inductance, restricting their use to low-frequency AC or DC measurements.