Lesson: Relating emf, Current, Internal Resistance, and Terminal Voltage

In this lesson, we will learn how to calculate the current produced by voltage sources with internal resistance when connected to external resistances.

Sample Question Videos

01:28

Worksheet: 10 Questions • 1 Video

Q1:

A battery of emf 6.00 V has an internal resistance of 0.0833 Ω.

What current would be produced if the battery terminals were momentarily shorted together by a connector with negligible resistance?

The battery is connected to a circuit and produces a 0.250 A current. What is the battery’s terminal voltage?

Q2:

The terminal voltage of a 3.60 V emf cell with an internal resistance of 0.250 Ω is measured by placing a 4.00 kΩ voltmeter across the battery’s terminals, as shown in the accompanying diagram.

What is the current in the voltmeter?

What is the terminal voltage of the battery?

What is the ratio of the terminal voltage of the battery to its emf?

Q3:

An automobile starter motor has an equivalent resistance of 0.0700 Ω and is supplied by a battery with a terminal voltage of 15.0 V that has a 0.0200 Ω internal resistance.

What is the current supplied to the motor?

What is the emf applied on the battery?

What power is supplied to the motor by the battery?

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