Ammeter

Definition

An ammeter is an electrical instrument used to measure the electric current flowing through a circuit. It is a crucial component in the study of DC voltmeters and ammeters, as it allows for the direct measurement of the current passing through a specific point in an electrical system.

5 Must Know Facts For Your Next Test

1. Ammeters are designed to be connected in series with the circuit or component being measured, as they measure the current flowing through them.
2. The ammeter must have a low resistance to avoid significantly altering the current in the circuit being measured, a property known as the ammeter's internal resistance.
3. Ammeters can be classified as analog or digital, with digital ammeters providing more accurate and precise measurements.
4. Ammeters can measure both AC (alternating current) and DC (direct current) circuits, with different ammeter designs required for each type of current.
5. The selection of an appropriate ammeter range is crucial to ensure accurate measurements and avoid overloading the instrument, which could potentially damage it.

Review Questions

• Explain the purpose and working principle of an ammeter in an electrical circuit.
  • The primary purpose of an ammeter is to measure the electric current flowing through a specific point in an electrical circuit. It works by being connected in series with the circuit or component being measured, allowing the ammeter to directly measure the current passing through it. This is in contrast to a voltmeter, which is connected in parallel to measure the voltage difference across a component or section of the circuit. The ammeter must have a low internal resistance to avoid significantly altering the current being measured, and the appropriate ammeter range must be selected to ensure accurate readings and prevent damage to the instrument.
• Describe the differences between analog and digital ammeters and the factors to consider when selecting an ammeter for a particular application.
  • Analog ammeters use a moving needle to indicate the current measurement, while digital ammeters display the current value numerically. Digital ammeters generally provide more accurate and precise measurements compared to analog models. When selecting an ammeter, factors to consider include the type of current (AC or DC), the expected current range, the required accuracy and resolution, and the internal resistance of the ammeter. The ammeter must be chosen with a range that is appropriate for the circuit being measured to ensure accurate readings and avoid overloading the instrument, which could potentially damage it.
• Analyze the relationship between current, resistance, and voltage in an electrical circuit, as described by Ohm's Law, and explain how an ammeter can be used to verify this relationship experimentally.
  • Ohm's Law states that the voltage (V) across a resistor is directly proportional to the current (I) flowing through it, and inversely proportional to the resistance (R) of the resistor, as expressed by the equation $V = IR$. An ammeter can be used to experimentally verify this relationship by measuring the current flowing through a resistor while also measuring the voltage across the resistor. By varying the resistance or the voltage and measuring the corresponding changes in current, the experimenter can demonstrate the validity of Ohm's Law and the interconnected nature of these fundamental electrical quantities. This allows for a deeper understanding of the principles governing the behavior of electrical circuits and the role of the ammeter in measuring and validating these relationships.

Related terms

Current: The rate of flow of electric charge, typically measured in amperes (A).

Resistance: The opposition to the flow of electric current, measured in ohms (Ω).

Ohm's Law: The relationship between current, voltage, and resistance in an electrical circuit, expressed as $V = IR$.