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

Physics

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

Q1:

What is the internal resistance of a voltage source if its terminal potential drops by 2.00 V when the current supplied increases by 5.00 A?

Q2:

A child’s electronic toy is supplied by three 1.58 V alkaline cells, in series with a 1.53 V carbon–zinc dry cell. The cells supply power to a load of resistance 10.0 Ω. The alkaline cells have internal resistances of 0.0200 Ω and the dry cell has an internal resistance of 0.100 Ω.

What is the total current in the toy?

How much power is supplied to the load?

What would the internal resistance of the dry cell be if it goes bad, resulting in only 0.500 W being supplied to the load?

Q3:

Consider the circuit shown. Each battery has an emf of 1.50 V and an internal resistance of 1.00 Ω.

What is the current through the external resistor, which has a resistance of 10.00 ohms?

What is the terminal voltage of each battery?

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