GCSE·4 mins·02/11/21

# GCSE Physics - Electricity

What have you already covered at KS3 that you will build on at GCSE Level?

• At KS3 you will have probably had the circuit kits out at some point.
• You will have learned about what materials allow electricity to flow through them and named them as conductors and those that don’t, resistors.
• Most likely, you will have built a complete circuit that lights a bulb and then a series and parallel circuit. Doing this, you will have learned that bulbs go dimmer when you add them to a series circuit but that they stay the same brightness when you add them in parallel.
• You may have discussed that electrical energy is shared in series and not in parallel and that a parallel circuit will drain a battery more quickly than series.
• You may have been introduced to the idea that the battery provides a push for the current in a circuit and maybe that the current is linked to electrons flowing in the wire.
• You may even have seen some of the following symbols when working with circuit diagrams:

Topics

GCSE electricity is a BIG topic! A lot of what you will cover will be new to you and more advanced than anything you did at KS3:

• Current, potential difference and resistance
• Series and Parallel Circuits
• Domestic uses and safety.
• Energy transfers in appliances and the National Grid (some efficiency work here).
• Static electricity

### To prepare for GCSE electricity questions...

Firstly, you are allowed to use a calculator for all of the maths problems in the exam!

The practical element of the exam will be examined in the exam paper and it will require you to either plan an investigation or discuss the findings from an example of an investigation that will be given to you. Don’t worry, you will have met all of these practicals as you progress through the course. The practicals are:

• using circuit diagrams to construct appropriate circuits to investigate the I–V characteristics of a variety of circuit elements, including a filament lamp, a diode and a resistor at constant temperature (you will need to learn the graphs that you produce).
• using circuit diagrams to set up and check appropriate circuits to investigate the factors affecting the resistance of electrical circuits, which will include:
• the length of a wire at a constant temperature
• combinations of resistors in series and parallel.
• You will need to recall the three graphs for electrical resistance as well as be able to discuss two others for LDRs and thermistors. LEARN THEM.

Hints and tips:

• You will need to recall the following and apply them:

charge flow (Q) = current (I) × time (t)

potential difference (V) = current (I) × resistance (Ω)

Power (W) = potential difference (V) × current (I)

power (W) = current2 (I2) × resistance (Ω)

energy transferred (J) = power (W) × time (t)

energy transferred (J) = charge flow (Q) × potential difference (V)

Rtotal = R1 + R2 (Ω) (in series)

• Write all of your numbers down, even if you get the wrong answer you can be awarded marks for your method in working it out!
• Remember mains electricity is 230V and 50Hz
• Units! Units are another thing you will have to remember for the exam. They are often worth a mark, so they are easy ways to increase your score and push you into the next grade boundary!

On long answer questions: There is also an element of extended writing that can include topics from electricity, which will contribute to your SPG grade. These longer answer questions are usually awarded 6 marks and are evaluated on a basis of three tiers of content.

• Common questions often cover advantages/disadvantage discussions for example two types of electricity production. You may be asked to explain how a transformer works or use a little bit of maths to work out the value of something in order to compare it with another, for example perhaps a discussion of power losses in cables.
• Bullet points are absolutely allowed as long as each bullet point is a complete sentence and relevant to the answer.

Final words...

There is a lot of new information on this topic and that can’t be avoided. But look for the patterns, see how atoms, current and static are linked, and realise how potential difference is just another way of measuring energy. See where the electricity topic overlaps with the other energy topics and use it as a way to condense how much you need to learn, for example with the transformers and efficiency elements and linking with what you know about atoms from the atomic physics unit and your chemistry. And remember most electrical energy is wasted as heat in the wires which heat up when used.

Resources for this topic:

If you can find it, there is an amazing film about the early discoveries in electricity called Spark.

Past papers can be found at the main exam board websites and also here: https://revisionscience.com/gcse-revision/physics/physics-gcse-past-papers

Jennifer Taylor BSc, MSc, PGCE, MInstPhysics.

I have been teaching Physics since 2006. In this time I have been twice nominated for the National Teaching Awards and my results have been among the best in the country.

I am an Expert Examiner for Pearson EDEXCEL and continue to send the message to students that Physics is fun and it doesn’t need to be complicated!