Lesson 3.5.1.6
3.5.1.6 Electromotive force and internal resistance Quiz: AQA Physics, Unit 5
20 questions
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Lesson 3.5.1.6, Electromotive force and internal resistance: 20 multiple choice questions for the AQA Physics (7408), Unit 5: Electricity, written with Revision Ninja.
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The 20 questions
-
The electromotive force (emf) of a source is defined as:
- the energy transferred by the source per unit charge passing through it
- the pd across its terminals when current flows
- the power delivered per unit charge
- the charge transferred per unit energy
-
Terminal potential difference of a cell with emf E, internal resistance r and current I is:
- E / (Ir)
- IR only, the external resistance
- E + Ir
- E - Ir
-
The emf equation for a complete circuit is:
- E = I / (R + r)
- E = I R
- E = I(R + r)
- E = (R + r) / I
-
The gradient of a graph of terminal pd against current is:
- the external resistance
- the emf of the cell
- the power dissipated
- the negative of the internal resistance
-
The y-intercept of a graph of terminal pd against current, at zero current, gives:
- the external resistance
- the short-circuit current
- the internal resistance
- the emf
-
When the external resistance is much greater than the internal resistance, the terminal pd is:
- twice the emf
- close to the emf
- close to zero
- equal to the internal resistance
-
The short-circuit current of a cell with emf E and internal resistance r is:
- E / r
- E x r
- E + r
- E / (R + r)
-
A 1.5 V cell with internal resistance 0.50 ohm is connected to a 2.5 ohm resistor. What is the terminal pd?
- 1.5 V
- 2.0 V
- 1.25 V
- 0.75 V
-
A 1.5 V cell with internal resistance 0.50 ohm is connected to a 2.5 ohm resistor. What is the current?
- 0.50 A
- 0.60 A
- 3.0 A
- 1.5 A
-
A battery has emf 12 V and internal resistance 0.40 ohm. What is its short-circuit current?
- 12.4 A
- 30 A
- 3.0 A
- 4.8 A
-
A 6.0 V cell with internal resistance 2.0 ohm drives a current through a 10 ohm external resistor. What is the lost volts?
- 1.0 V
- 2.0 V
- 5.0 V
- 0.5 V
-
Measurements on a cell give terminal pd 8.4 V at 0.50 A and 7.8 V at 1.0 A. What is the emf?
- 8.4 V
- 9.0 V
- 7.8 V
- 10.2 V
-
The terminal pd of a cell is 9.0 V with no current and falls to 7.5 V at a current of 2.0 A. What is the internal resistance?
- 0.75 ohm
- 4.5 ohm
- 1.5 ohm
- 0.13 ohm
-
A 12 V cell supplies a steady 2.0 A for 10 minutes. What total energy is transferred by the cell?
- 14.4 kJ
- 1.44 kJ
- 7.2 kJ
- 144 kJ
-
In an experiment on a cell, which graph gives its emf and internal resistance?
- current on the vertical axis against terminal pd on the horizontal axis with zero intercept
- terminal pd on the vertical axis against current on the horizontal axis
- resistance against time
- power against time
-
A 1.5 V cell with internal resistance 1.0 ohm drives a 2.0 ohm external resistor. What power is dissipated in the external resistor?
- 0.25 W
- 0.50 W
- 1.0 W
- 0.75 W
-
Two identical 1.5 V cells, each with internal resistance 0.20 ohm, are in series with a 2.6 ohm resistor. What is the current?
- 0.5 A
- 3.0 A
- 1.2 A
- 1.0 A
-
Two identical cells, each 1.5 V with internal resistance 0.60 ohm, are in parallel with a 2.4 ohm resistor. What is the current?
- 1.0 A
- 0.63 A
- 0.56 A
- 0.25 A
-
A student claims the terminal pd equals the emf whenever the circuit is closed. Which response is best?
- Incorrect: once current flows the terminal pd falls by Ir, so it equals the emf only when I is zero.
- Correct: the terminal pd is always equal to the emf.
- Incorrect, because the terminal pd is always zero in a closed circuit.
- Correct, because internal resistance is negligible in all real cells.
-
A 12 V cell with internal resistance 0.50 ohm drives a 5.5 ohm lamp. What power does the lamp dissipate?
- 22 W
- 44 W
- 2.0 W
- 11 W
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