How is current measured with an in-line type meter?
A. by placing a voltmeter in series with the circuit
B. by placing an ammeter in series with the circuit
C. by placing a voltmeter in parallel with the circuit
D. by placing an ammeter in parallel with the circuit
The Correct Answer and Explanation is:
The correct answer is:
B. by placing an ammeter in series with the circuit
Explanation:
Current is the flow of electric charge through a conductor, measured in amperes (A). To measure the electric current in a circuit, an ammeter is used. The ammeter is designed to have very low resistance so that it does not significantly alter the current flowing through the circuit. For accurate measurement of the current, the ammeter must be connected in series with the load or component in the circuit.
Why is an ammeter placed in series?
- Series Connection: In a series connection, all the current flowing through the circuit also flows through the ammeter. This allows the ammeter to measure the total current that is passing through that part of the circuit. If the ammeter were placed in parallel, it would bypass the load, and the current would not flow through the ammeter in the correct manner, leading to inaccurate readings or possible damage to the meter.
- Low Resistance: Ammeter devices are constructed with very low resistance to avoid limiting or interfering with the current flow. By placing the ammeter in series, it allows for the current to pass through without creating a significant voltage drop or altering the current in the circuit.
Incorrect Options:
- A. by placing a voltmeter in series with the circuit: A voltmeter is used to measure the voltage (or potential difference) across a component, not the current. Placing a voltmeter in series would disrupt the current flow, as voltmeters have very high resistance.
- C. by placing a voltmeter in parallel with the circuit: A voltmeter is correctly placed in parallel to measure voltage, but this would not give any information about the current.
- D. by placing an ammeter in parallel with the circuit: If an ammeter were placed in parallel with a component, it would act as a short circuit and likely damage both the ammeter and the circuit, leading to incorrect measurements or unsafe conditions.
In summary, to measure the current accurately, an ammeter must be placed in series with the circuit, allowing the meter to measure the current passing through the circuit without causing any disruption to the flow.