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Year 11
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Higher

Danger from electric shock

I can describe mains electricity in the UK and the dangers of an electric shock.

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New
New
Year 11
OCR
Higher

Danger from electric shock

I can describe mains electricity in the UK and the dangers of an electric shock.

Download all resources
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Share activities with pupils
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Lesson details

Key learning points

  1. Mains electricity has a p.d. of 230 V between a live wire connection (230 V) and a neutral wire connection (0 V).
  2. Mains electricity has alternating current at a frequency of 50 Hz.
  3. Electric current passing through a person’s body can damage living tissue and/or stop their heart pumping blood.
  4. The size of current from a shock depends on the p.d. across the person and the resistance of their skin (I = V ÷ R).
  5. Wet skin has a much lower resistance than dry skin, and a smaller p.d. can cause a bigger current from a shock.

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

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.

Ideas about mains electricity build on many different ideas covered in GCSE electricity topics. In this lesson, pupils consolidate their understanding of potential difference (between live and neutral wires) and encounter the equation I = V ÷ R in the context of electric shocks.
Teacher tip

Content guidance

  • Depiction or discussion of sensitive content

Supervision

Adult supervision recommended

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).

Lesson video

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Starter quiz

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6 Questions

Q1.
A battery provides DC, which stands for …
Correct Answer: direct current
Q2.
Which of the following equals a milliamp?
1000 A
100 A
0.1 A
Correct answer: 0.001 A
0.0001 A
Q3.
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.
Correct answer: It reverses the current.
It has no effect on the current.
It makes the current stop flowing.
Q4.
Which of the following statements is correct?
In a circuit, the current and p.d. determine the resistance.
Correct answer: In a circuit, the p.d. and resistance determine the current.
In a circuit, the resistance and current determine the p.d.
Q5.
How many of the following are good electrical conductors? rubber, copper, tap water, sea water
one
two
Correct answer: three
four
Q6.
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
Correct answer: 7 V
10 V

Exit quiz

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6 Questions

Q1.
Mains electricity is AC, which stands for …
Correct Answer: alternating current
Q2.
What colour is the insulation of the neutral wire in a mains circuit?
Correct answer: blue
brown
green and yellow
red
white
Q3.
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
Correct answer: switching between +230 V and −230 V
Q4.
Which of the following cause an electric shock?
Correct answer: touching the ground and a live wire at the same time
Correct answer: touching a neutral wire and a live wire at the same time
touching a neutral wire and the ground at the same time
Q5.
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?
Correct answer: 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.
Correct answer: Wet skin has a lower resistance than dry skin.
Q6.
A person gets an electric shock from the mains. Their skin has a resistance of 25 kΩ. The current through their body is A.
Correct Answer: 0.0092, 0.00920, .0092, 0.0092 A, 0.0092A