Current is measured with an instrument which is called a (an) ...................

(A) Ammeter

(B) Voltmeter

(C) Meter Bridge

(D) Galvanometer.

To determine the correct instrument for measuring current, let's look at the options provided. The right choice is (A) Ammeter. An ammeter is specifically designed to measure the flow of electric current in a circuit, typically expressed in amperes (A).

Understanding the Instruments

Each of the options listed serves a different purpose in electrical measurements:

• Ammeter: This device is connected in series with the circuit to measure the current flowing through it. It provides a direct reading of the current in amperes.
• Voltmeter: Unlike an ammeter, a voltmeter measures the potential difference (voltage) across two points in a circuit. It is connected in parallel and reads voltage in volts (V).
• Meter Bridge: This is a device used to measure resistance, not current. It operates on the principle of a Wheatstone bridge and is typically used in laboratory settings.
• Galvanometer: This instrument can detect small currents and is often used to measure current indirectly. However, it is not as straightforward as an ammeter for general current measurement.

How an Ammeter Works

An ammeter works by allowing current to pass through a coil within the device. The magnetic field generated by this current interacts with a needle or a digital display, providing a reading of the current's strength. When using an ammeter, it’s crucial to connect it correctly in series with the circuit to ensure accurate measurements.

Practical Example

Imagine you have a simple circuit with a battery, a resistor, and a light bulb. To measure how much current is flowing through the circuit, you would place an ammeter in series with the light bulb. If the ammeter reads 2 A, it indicates that 2 amperes of current are flowing through the circuit.

Summary of Key Points

In summary, the correct answer to your question is (A) Ammeter, as it is the instrument specifically designed for measuring electric current. Understanding the roles of different instruments is essential for anyone studying electricity and electronics, as it helps in selecting the right tool for the task at hand.