Starter quiz
- Match each of the following quantities to their correct definitions.
- current⇔charge flowing past a point in a circuit per second ✓
- electric charge⇔a property that can either be positive or negative ✓
- potential difference⇔energy transferred per unit charge passing between two points ✓
- Match each of the following quantities to the correct measurement units.
- current⇔A ✓
- energy⇔J ✓
- potential difference⇔V ✓
- power⇔W ✓
- ______ is the amount of energy transferred per second.
- 'power' ✓
- A metal is made of ions and free electrons. What is the charge on the ions?
- negative
- neutral
- positive ✓
- positive in some metals and negative in others
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- 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?
- The current in B is half the current in A.
- The current in B is twice the current in A.
- The resistance in B is twice the resistance in A. ✓
- The p.d. across the battery in B is twice the p.d. across the cell in A. ✓
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- A mains appliance has a current of 3.50 A through it. The power of the appliance is ______ W (to 3 sf).
- '805' ✓
Exit quiz
- An ammeter shows a steady reading of 1 A. Which of the following statements describes what this means?
- 1 ampere flows through per second.
- 1 coulomb flows through per second. ✓
- 1 coulomb flows through per ampere.
- 1 joule is transferred per second.
- 1 joule is transferred per coulomb.
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- Match the following symbols for quantities to the symbols used for their units.
- ⇔J ✓
- ⇔A ✓
- ⇔W ✓
- ⇔C ✓
- ⇔s ✓
- ⇔V ✓
- 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
- 10 C ✓
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- 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.
- '12' ✓
- 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
- 90 J ✓
- 230 J
- 590 J
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- 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.
- 1700 J. ✓
- 3700 J.
-
Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Electric charge, Q, is measured in coulombs (C).
- Electric current is a measure of the rate of flow of electric charge, calculated using: I = Q ÷ t.
- Potential difference is a measure of the energy transferred by each coulomb of charge, calculated using: V = E ÷ Q.
- Combining I = Q ÷ t and V = E ÷ Q gives the equation: E ÷ t = I × V. This is equivalent to P = I × V.
- 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
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