Linking current, potential difference and resistance
Lesson details
Learning outcome
I can describe the relationships between current, potential difference and resistance.
Key learning points
- The current in a series circuit is the same everywhere.
- The p.d. across each component in a series electric circuit adds up to the p.d. of the battery.
- The greater the resistance in a series circuit, the lower the current (current is inversely proportional to resistance).
- The greater the battery p.d. in series circuit, the larger the current (current is directly proportional to p.d.).
- Current, p.d. or resistance can be calculated with the equation: current = p.d./resistance.
Keywords
Series circuit - a circuit where there is only one loop
Potential difference (p.d.) - the voltage or a measure of the ‘push’ on electrons in a circuit
Resistance - a measure of how difficult it is for current to flow in a circuit
Electrical current - a measure of the amount of charge passing a given point in one second
Ohms (Ω) - the unit of resistance
Common misconception
Pupils often use physics equations without understanding, leading to errors.
Develop a qualitative understanding of potential difference, current and resistance before combining them mathematically. Use the equation as a shorthand for an already understood relationship between them.
Teacher tip
Provide opportunity for pupils to explain what they think is likely to happen in a range of different circuit examples before they calculate their answers.
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.The number of coulombs that flow past a point each second equals the…
Q2.The unit of current is the…
Q3.A circuit which has only one loop is called a circuit.
Q4.In a circuit, electrons flow through the wires away from the end of the battery.
Q5.In a circuit with a single loop, which of the following statements are correct?
Q6.The equation relating current, charge and time is: current = charge ÷ time. Which of the following equations is the correct rearrngement of the equation with time as the subject?
Assessment exit quiz
6 Questions
Q1.Match the following quantities to its definition.
a measure of how difficult it is for charge to move around a circuit
the amount of charge passing a point in one second
a measure of the ‘push’ on electrons in a circuit
Q2.A series circuit contains only a cell and a lamp. Which of the following changes occurs if another lamp is added, in series with the first lamp?
Q3.In a series circuit, there is a particular type of relationship between current and total resistance: the current is proportional to the total resistance, if the p.d. stays the same.
Q4.The potential difference across a 10 Ω resistor in a circuit is 4.0 V. What is the current in the resistor?
Q5.A motor has a resistance of 6.0 Ω. What p.d. is needed to make a current of 1.5 A flow through the motor?
Q6.A pupil has identical lamps and identical cells. He connects two cells and two lamps in series. Then he changes the circuit, but the current does not change. Which of the following could he have done?
To help you plan your 10 physics lesson on: Linking current, potential difference and resistance, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 physics lesson on: Linking current, potential difference and resistance, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 physics lessons from the Electric fields and circuit calculations unit, dive into the full secondary physics curriculum, or learn more about lesson planning.