What is Ammeter – Basic Definition, Working & It’s Application


The ammeter, a cornerstone instrument in the field of electrical engineering, plays a vital role in measuring electric current. From small-scale circuits to industrial power systems, ammeters are essential tools for assessing and monitoring the flow of electrical current. In this article, we shall discuss about the ammeters, including their definitions, key features, construction, working principles, various types, and it’s applications.

Definitions of Ammeter

An ammeter is a specialized instrument designed to measure electric current, expressed in units like amperes (A) or milliamperes (mA). It provides valuable insights into the amount of current flowing through a particular section of an electrical circuit, making it a crucial tool for troubleshooting and analysis.

Features of Ammeter

  • Current Range Selection: Ammeters come with adjustable current ranges to accommodate a wide spectrum of current values.
  • High Accuracy: Precision is paramount in current measurements, and quality ammeters offer high levels of accuracy.
  • Digital or Analog Display: Ammeters can have either digital displays for precise readings or analog indicators for quick assessments.
  • Low Insertion Resistance: Ammeters are designed with minimal internal resistance to prevent voltage drops and maintain circuit integrity.
  • Safety Features: Many ammeters incorporate safety features like overload protection to safeguard the instrument and the operator.

Construction of Ammeter

Ammeters consist of essential components, including a shunt resistor (to divert current), a display mechanism (analog or digital), and circuitry to convert the measured current into a readable format. Input terminals enable connection to the section of the circuit under investigation, and protective casings ensure safety and durability.

Working of Ammeter

Ammeters operate based on the principle of Ohm’s law, which relates current (I), voltage (V), and resistance (R) through the equation: I = V/R. When an ammeter is connected in series with a circuit, it measures the current passing through it. The voltage drop across the shunt resistor is proportional to the current, allowing the ammeter to display the current value.

Types of Ammeter

There are mainly two types of ammeters:

  • Analog Ammeter
  • Digital Ammeter

Analog Ammeters

These have a needle or pointer that moves across a scale to indicate current values.

Digital Ammeters

These display current readings in digital numerical format, providing higher precision and ease of use.

Applications of Ammeter

  • Circuit Analysis: For assessing current flow in electronic circuits.
  • Electrical System Maintenance: In industrial settings to monitor and maintain machinery.
  • Battery Testing: To check the charge and discharge currents of batteries.
  • Automotive Diagnostics: To troubleshoot electrical issues in vehicles.
  • Laboratory Experiments: In scientific research and educational laboratories for current measurements.

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