New
New
Year 11
AQA
Higher

Calculating with electric charge: including complex calculations

I can explain the equations: I = Q ÷ t, V = E ÷ Q, P = I × V, and V = I × R, and use them in calculations.

New
New
Year 11
AQA
Higher

Calculating with electric charge: including complex calculations

I can explain the equations: I = Q ÷ t, V = E ÷ Q, P = I × V, and V = I × R, and use them in calculations.

Lesson details

Key learning points

  1. Electric charge, Q, is measured in coulombs (C).
  2. Electric current is a measure of the rate of flow of electric charge, calculated using: I = Q ÷ t.
  3. Potential difference is a measure of the energy transferred by each coulomb of charge, calculated using: V = E ÷ Q.
  4. Combining I = Q ÷ t and V = E ÷ Q gives the equation: E ÷ t = I × V. This is equivalent to P = I × V.
  5. Unknown variables in the power equation can often be calculated using: I = V ÷ R.

Common misconception

Understanding electrical circuits is about memorising equations and procedures.

Give pupils the opportunity to discuss what happens in a circuit before they attempt to answer questions about it.

Keywords

  • Electric current - an electrical property; it can either be positive or negative

  • Coulombs (C) - the unit of electric charge

  • Electric current - the amount of electric charge flowing past a point in a circuit each second

  • Potential difference (p.d.) - the amount of energy transferred by each coulomb of charge, passing between two points in a circuit

  • Power - the amount of energy transferred each second

This lesson is focused on exploring how moving charges relate to electric circuit equations. It provides an opportunity for pupils to practice with a wide range of past exam questions on electric circuits, from across much of the syllabus.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
Match each of the following quantities to their correct definitions.
Correct Answer:current,charge flowing past a point in a circuit per second

charge flowing past a point in a circuit per second

Correct Answer:electric charge,a property that can either be positive or negative

a property that can either be positive or negative

Correct Answer:potential difference,energy transferred per unit charge passing between two points

energy transferred per unit charge passing between two points

Q2.
Match each of the following quantities to the correct measurement units.
Correct Answer:current,A

A

Correct Answer:energy,J

J

Correct Answer:potential difference,V

V

Correct Answer:power,W

W

Q3.
is the amount of energy transferred per second.
Correct Answer: power, Power
Q4.
A metal is made of ions and free electrons. What is the charge on the ions?
negative
neutral
Correct answer: positive
positive in some metals and negative in others
Q5.
In circuits A and B, all of the cells are identical and all of the lamps are identical. Which of the following statements are correct?
An image in a quiz
The current in B is half the current in A.
The current in B is twice the current in A.
Correct answer: The resistance in B is twice the resistance in A.
Correct answer: The p.d. across the battery in B is twice the p.d. across the cell in A.
Q6.
A mains appliance has a current of 3.50 A through it. The power of the appliance is W (to 3 sf).
Correct Answer: 805, 805 W, 805W

6 Questions

Q1.
An ammeter shows a steady reading of 1 A. Which of the following statements describes what this means?
1 ampere flows through per second.
Correct answer: 1 coulomb flows through per second.
1 coulomb flows through per ampere.
1 joule is transferred per second.
1 joule is transferred per coulomb.
Q2.
Match the following symbols for quantities to the symbols used for their units.
Correct Answer:$$E$$,J

J

Correct Answer:$$I$$,A

A

Correct Answer:$$P$$,W

W

Correct Answer:$$Q$$,C

C

Correct Answer:$$t$$,s

s

Correct Answer:$$V$$,V

V

Q3.
How much charge flows through a motor in 5.0 s if there is a constant current of 2.0 A?
0.40 C
2.5 C
3.0 C
7.0 C
Correct answer: 10 C
Q4.
66 J of energy is transferred to a lamp when 5.5 C of charge flows through it. The potential difference across the lamp is V.
Correct Answer: 12, 12 V, 12V, twelve, 12 volts
Q5.
The potential difference across a television is 230 V and a steady current of 0.39 A flows through it. How much energy does the television transfer every second?
17 J
35 J
Correct answer: 90 J
230 J
590 J
Q6.
An electric fan has resistance 5.2 Ω. When a current of 2.3 A flows through the heater, the energy transferred in one minute is …
28 J.
60 J.
720 J.
Correct answer: 1700 J.
3700 J.