Chapter 19, Problem 22Q

To determine

To Explain:

Why an ideal ammeter should have 0 resistance while an ideal voltmeter should have infinite resistance?

Answer to Problem 22Q

Solution:

• Ideal ammeter should have 0 resistance so that all the current pass through it.
• Ideal voltmeter should have infinite resistance so that no current pass through it.

Explanation of Solution

According to ohm’s law current always follow the path of least resistance.

Ammeter: Ammeter is a device used to measure the current in a circuit. As the ammeter wire has very low resistance still it offers some resistance to the flow of current, it cannot measure the actual reading of current in the circuit. Therefore, in order tomeasure the actual reading of current in the circuit an ideal ammeter should have 0 resistance.

Voltmeter: Voltmeter is a device used to measure the voltage in a circuit. If the voltmeter wire has lower resistance than it draws the high amount of current from the circuit, it reduces the actual reading of voltage from the circuit. Therefore, in order to measure the accurate reading of voltage from the circuit, the voltmeter should have infinite resistance so that no current can pass through the voltmeter.