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SavannahYear 8
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ScienceElectricity, magnetism and space26 min★★ difficulty

Current, potential difference and circuits

Series and parallel circuits behave very differently — and understanding current and potential difference explains why.

Part of your national curriculum
  • Physics: electricity and magnetism: Understand electric current, measured in amperes, in circuits, series and parallel circuits, and potential difference measured in volts

Lesson overview

What you'll learn in this lesson

Understand electric current, measured in amperes, in circuits, series and parallel circuits, and potential difference measured in volts

Key learning points

  • • Current and potential difference
  • • Series circuits
  • • Parallel circuits

This lesson at a glance

  • 26 minutes
  • 14 parts to scroll through
  • 3 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

electriccurrentmeasuredamperescircuits

Scroll down — the lesson carries on below

Part 1 of 14 · Discover7%
1

Watch & discover

Part 1 of 14

Watch first

Current, potential difference and circuits

An English teaching video on this topic from Lammas Science. Watch it, then scroll down for the lesson.

In a nutshell

Understand electric current, measured in amperes, in circuits, series and parallel circuits, and potential difference measured in volts

2

Learning cycle

Part 2 of 14

Learning cycle 1 of 2

Part 1 · Current and potential difference

A short piece of teaching, then a check to make sure it has landed.

3

Explore the idea

Part 3 of 14

Learn

Current and potential difference

Electric current is the rate of flow of charge, measured in amperes (A) with an ammeter connected in series. Potential difference (voltage) is the energy transferred per unit charge between two points, measured in volts (V) with a voltmeter connected in parallel across a component.

4

Explore the idea

Part 4 of 14

Learn

Series circuits

In a series circuit, there is only one loop, so the current is the same everywhere in the circuit. The potential difference from the supply is shared between components — the more components, the smaller the share (and often the dimmer the bulbs) each one gets.

5

Quick check

Part 5 of 14

Quick check

What instrument measures current, and how is it connected?

6

Reset break

Part 6 of 14

Pause

That's sitting 1 of 2 done

Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.

Stop here for now
7

Quick check

Part 7 of 14

Quick check

In a series circuit with two identical bulbs, how does the current compare at different points?

8

Learning cycle

Part 8 of 14

Learning cycle 2 of 2

Part 2 · Parallel circuits

A short piece of teaching, then a check to make sure it has landed.

9

Explore the idea

Part 9 of 14

Learn

Parallel circuits

In a parallel circuit, components are connected in separate branches. The potential difference across each branch is the same as the supply, but the current splits between branches, and each branch can be switched independently — useful for household wiring.

10

Quick check

Part 10 of 14

Quick check

In a parallel circuit, what happens to potential difference across each branch?

11

Challenge round

Part 11 of 14

Game · Sort it

Which of these are true?

Drag each card into the right column. Tap a card first if dragging is fiddly.

True

Not true

12

Challenge round

Part 12 of 14

Game · Fill the gaps

Finish the sentences

Choose the word that belongs in each gap.

____ current is the rate of flow of charge, measured in amperes (A) with an ammeter connected in series.

Potential difference (voltage) is the energy transferred per unit charge between two points, ____ in volts (V) with a voltmeter connected in parallel across a component.

In a series circuit, there is only one loop, so the ____ is the same everywhere in the circuit.

13

Mastery quiz

Part 13 of 14

Marked quiz

End of lesson quiz: Current, potential difference and circuits

3 questions, marked with the reasoning shown. No timer.

  1. 1. What instrument measures current, and how is it connected?

  2. 2. In a series circuit with two identical bulbs, how does the current compare at different points?

  3. 3. In a parallel circuit, what happens to potential difference across each branch?

14

Lesson round-up

Part 14 of 14

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 3 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Case study

Why the school greenhouse failed

A science club grew tomato plants in the school greenhouse. In June the plants grew well: leaves were dark green and the fruit set quickly. In July the club went away for two weeks and left the greenhouse door shut. When they came back, the leaves were curled and pale and most of the fruit had dropped.

The club had a data logger inside. It showed the temperature reached 46 °C on several afternoons and the soil moisture fell close to zero. The club knew photosynthesis needs light, water and carbon dioxide, and that enzymes in a plant work best in a narrow range of temperature. Above that range the enzymes stop working properly.

The club repeated the summer with the door propped open and a water bottle drip on each pot. Temperature peaked at 31 °C and the plants survived.

Written for Good Learning Co.

Reading questions

  1. Name the variable the club changed the second time, and one variable they kept the same.
  2. Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
  3. Write a conclusion for the club's report, saying how far the evidence supports it.

  • Method and results

    Writing

    Write the aim, what you changed, what you measured and what you kept the same, then record your results in a table.

    1 page + results table

  • Conclusion

    Writing

    Explain what your results show and why, using the scientific words from the lesson. Say how you know you can trust them.

    6–8 sentences

  • Labelled diagram

    Diagram

    Draw the apparatus or the process in pencil, label it fully, and photograph it.

    1 labelled diagram

  • Reading and notes

    Reading

    Read the lesson text again and write the key ideas in your own words.

    Half a page of notes

Saved as you type.

Part 1 of 14 · Watch & discover

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    Understand electric current, measured in amperes, in circuits, series and parallel circuits, and potential difference measured in volts

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