U6 Revision Quiz 2024 - EMF & Internal Resistance

A cell is connected across a resistor. After a while the internal resistance of the cell increases.

Which row of the table correctly shows the change in the current in the circuit and the change in the terminal potential difference across the cell?

• A

• B

• C

• D

A student carried out an experiment to determine the electromotive force (e.m.f.) of a cell. The current in a circuit was changed by adjusting a variable resistor. A graph was plotted of the voltmeter reading on the y‑axis against the ammeter reading on the x‑axis.

Using the data obtained, the value of the intercept on the y‑axis was the e.m.f. of the cell.

Which of the following circuits should have been used?

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A cell of emf 1.5 V is connected to a 5.0 Ω resistor. The terminal potential difference across the cell is 1.0 V.

Which of the following is the current in the circuit?

• 0.10 A

• 0.20 A

• 0.30 A

• 0.50 A

A resistor is connected to a cell. An amount of charge Q passes through the resistor in a time t. During this time, the amount of chemical energy converted to electrical energy by the cell is E.

Select the row of the table which correctly gives the current in the resistor and the e.m.f. of the cell.

• A

• B

• C

• D

A cell with emf ε and internal resistance r has a potential difference V across its terminals when the current is I.

The internal resistance r is given by

The circuit shows a resistor of resistance R connected to a cell of e.m.f. ε and internal resistance r. When the current in the circuit is I the terminal potential difference is V.

Which of the following is an expression for the power P dissipated in the internal resistance of the cell?

A cell of internal resistance 0.5 Ω is connected to a fixed resistor of resistance 10 Ω.

The resistance of the resistor is changed to 20 Ω.

Which statement is not correct?

• The current in the circuit will halve.

• The e.m.f. of the cell will remain constant.

• The power dissipated by the fixed resistor will decrease.

• The terminal p.d. of the cell will increase.

A resistor X of resistance 40 Ω and a variable resistor are connected to a battery of electromotive force (e.m.f.) 12 V and internal resistance 2.0 Ω, as shown.

The resistance of the variable resistor is changed from 0 to 40 Ω.

What is the change in power dissipated in resistor X?

• 2.4 W

• 2.7 W

• 3.6 W

• 5.6 W

A battery, with internal resistance, is connected to a parallel arrangement of two resistors and a switch S, as shown.

Initially switch S is open.

What happens to the voltmeter and ammeter readings when switch S is closed?

• A

• B

• C

• D

The diagram shows an electric circuit in which the resistance of the external resistor is 2R and the internal resistance of the source is R.

What is the ratio:

power in internal resistance ?

power in external resistor

• 0.25

• 0.50

• 2

• 4