Class 8 Science Chapter 9 : Ammeter and Voltmeter

03/12/2023 by abc

Today we are going to discuss about Ammeter and Voltmeter: from Class 8 Science Chapter 9 .

An ammeter and voltmeter are two important instruments used in electrical engineering and physics to measure the current and voltage in a circuit. They both work by measuring the electrical properties of a circuit and are essential tools for designing, troubleshooting, and repairing electrical systems.

Ammeter

An ammeter is an instrument used to measure the electric current in a circuit. It is typically connected in series with the circuit and measures the current flowing through it. The unit of measurement for current is the ampere (A), and an ammeter is calibrated in amperes.

To measure the current in a circuit using an ammeter, the circuit must be interrupted, and the ammeter must be inserted in series with the component whose current is to be measured. The ammeter should be connected in such a way that the current flows through it.

Formula for Ammeter:

The formula for calculating the current through a circuit using an ammeter is:

I = V/R

Where I is the current in amperes, V is the voltage across the circuit in volts, and R is the resistance of the circuit in ohms.

Example:

Suppose you have a circuit with a voltage of 10 volts and a resistance of 5 ohms. What is the current in the circuit?

I = V/R I = 10/5 I = 2 amperes

Therefore, the current flowing through the circuit is 2 amperes.

Voltmeter

A voltmeter is an instrument used to measure the potential difference (voltage) between two points in a circuit. It is typically connected in parallel with the circuit and measures the voltage across it. The unit of measurement for voltage is volts (V), and a voltmeter is calibrated in volts.

To measure the voltage in a circuit using a voltmeter, the voltmeter is connected in parallel across the component whose voltage is to be measured. The voltmeter should be connected in such a way that it is across the two points where the voltage is to be measured.

Formula for Voltmeter:

The formula for calculating the voltage across a circuit using a voltmeter is:

V = IR

Where V is the voltage in volts, I is the current flowing through the circuit in amperes, and R is the resistance of the circuit in ohms.

Example:

Suppose you have a circuit with a current of 5 amperes and a resistance of 10 ohms. What is the voltage across the circuit?

V = IR V = 5 x 10 V = 50 volts

Therefore, the voltage across the circuit is 50 volts.

An ammeter and voltmeter are important instruments used in electrical engineering and physics to measure the current and voltage in a circuit, respectively. They work by measuring the electrical properties of a circuit and are essential tools for designing, troubleshooting, and repairing electrical systems. By understanding the formulas and examples above, you can calculate the current or voltage in a circuit and use these instruments effectively.

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