When you insert a meter into a circuit to make a measurement, the meter will alt

Question

When you insert a meter into a circuit to make a measurement, the meter will alter the circuit. However, it should "disturb" the circuit as little as possible. Recall that you connect it in parallel with a resistor to measure voltage and you place it in series to measure current. When you set the meter to measure voltage, does it have a large resistance or a small resistance? When you set the meter to measure current, does it have a large resistance or a small resistance? Let's say that you have two resistors in series leading to three resistors in parallel and the equivalent resistance is 5 ohm. How much current flows if 20 V is placed across this network of resistors? (You only need to show one simple calculation.)

Explanation / Answer

(1) To measure the voltage in a circuit, a voltmeter is used and it must have high or large resistance.

(2) To measure the current in a circuit, an ammeter is used and it must have small resistance.

(3) Total equivalent resistance, R = 5 ohm.

Applied voltage, V = 20 V

So, the current, I = V / R = 20/5 = 4 A

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