Why an ammeter have a very low resistance and voltmeter have high resistance? ..how are they connected?
The correct answer and explanation is:
Correct Answer:
An ammeter has very low resistance to allow current to pass through it without significant opposition. A voltmeter has high resistance to prevent it from drawing current from the circuit. An ammeter is connected in series, while a voltmeter is connected in parallel.
Explanation (300 words):
In an electric circuit, measuring current and voltage requires the use of specialized instruments: the ammeter and the voltmeter. Each instrument is designed with specific resistance characteristics to ensure accurate measurements without disturbing the circuit.
An ammeter is used to measure the current flowing through a circuit. It must be connected in series with the component whose current is being measured. In a series connection, all the current flows through the ammeter. For accurate measurement, the ammeter must not interfere with the current flow. This is why it is designed with very low resistance. A low-resistance path ensures that the ammeter does not drop voltage across itself and does not alter the current flowing in the circuit. If an ammeter had high resistance, it would reduce the current it is supposed to measure and possibly distort the circuit operation.
On the other hand, a voltmeter is used to measure the potential difference (voltage) between two points in a circuit. It is always connected in parallel with the component across which the voltage is to be measured. In a parallel connection, the voltmeter should not draw significant current, or it could change the voltage of the component. To minimize current draw, a voltmeter is built with very high resistance. High resistance ensures that almost no current flows through the voltmeter, preserving the natural conditions of the circuit.
In conclusion, the design of these meters is based on their function: ammeters must allow current to pass with minimal resistance, while voltmeters must avoid drawing current. Their connection—series for ammeters and parallel for voltmeters—matches their operational purpose.