Starter quiz
- A battery provides DC, which stands for …
- 'direct current' ✓
- Which of the following equals a milliamp?
- 1000 A
- 100 A
- 0.1 A
- 0.001 A ✓
- 0.0001 A
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- A series circuit contains a battery and some resistors only. The connections to the battery are swapped. Which of the following statements about the effect of this change is correct?
- It increases the current.
- It decreases the current.
- It reverses the current. ✓
- It has no effect on the current.
- It makes the current stop flowing.
-
- Which of the following statements is correct?
- In a circuit, the current and p.d. determine the resistance.
- In a circuit, the p.d. and resistance determine the current. ✓
- In a circuit, the resistance and current determine the p.d.
-
- How many of the following are good electrical conductors? rubber, copper, tap water, sea water
- one
- two
- three ✓
- four
-
- One terminal of a power supply has a voltage of +5 V and the other terminal has a voltage of −2 V. Which of the following is the potential difference across the power supply?
- 2 V
- 3 V
- 5 V
- 7 V ✓
- 10 V
-
Exit quiz
- Mains electricity is AC, which stands for …
- 'alternating current' ✓
- What colour is the insulation of the neutral wire in a mains circuit?
- blue ✓
- brown
- green and yellow
- red
- white
-
- What is the voltage of the live wire in a UK mains circuit?
- 0 V
- switching between 0 V and +230 V
- switching between 0 V and −230 V
- switching between +230 V and −230 V ✓
-
- Which of the following cause an electric shock?
- touching the ground and a live wire at the same time ✓
- touching a neutral wire and a live wire at the same time ✓
- touching a neutral wire and the ground at the same time
-
- Which of the following explains why it is much more dangerous to get an electric shock when your skin is wet than when your skin is dry?
- Wet skin increases the current during a shock. ✓
- Wet skin increases the voltage during a shock.
- Wet skin has a higher resistance than dry skin.
- Wet skin has a lower resistance than dry skin. ✓
-
- A person gets an electric shock from the mains. Their skin has a resistance of 25 kΩ. The current through their body is ______ A.
- '0.0092' ✓
Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Mains electricity has a p.d. of 230 V between a live wire connection (230 V) and a neutral wire connection (0 V).
- Mains electricity has alternating current at a frequency of 50 Hz.
- Electric current passing through a person’s body can damage living tissue and/or stop their heart pumping blood.
- The size of current from a shock depends on the p.d. across the person and the resistance of their skin (I = V ÷ R).
- Wet skin has a much lower resistance than dry skin, and a smaller p.d. can cause a bigger current from a shock.
Common misconception
Mains appliances draw all their electricity from the live wire, without need for a complete circuit.
Show pupils live and neutral wires connected to a AC connections on a power pack (you can use individual wires taken from mains cables) to show complete circuits are necessary, and that mains cables contain these wires.
Keywords
Mains electricity - the electricity from electric sockets and circuits in a home
Live wire - a brown wire in a mains circuit that has a voltage of ±230 V
Neutral wire - a blue wire in a mains circuit that has a voltage of 0 V
Electric shock - a current passing through a person’s body that can be painful and sometimes harmful
Resistance - a property of materials that makes it harder for current to flow
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