Edexcel GCSE Physics 1PH0
Key Concepts of Physics
Motion and Forces
Conservation of Energy
Waves
Light and the Electromagnetic Spectrum
Radioactivity
Astronomy
Energy – Forces Doing Work
Forces and Their Effects
Electricity and Circuits
Static Electricity
Magnetism and the Motor Effect
Electromagnetic Induction
Particle Model
Electricity and Circuits
Resistance and the equation V = IR
- 2 things to know
- Paper 2
Overview
What resistance is, how a variable resistor dims a lamp and gives a range of readings, the ohm, and the equation linking potential difference, current and resistance with calculations.
What you need to know
Answer each one before you reveal it.
What happens to the current in a circuit if the resistance is increased while the potential difference stays the same?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is meant by the resistance of a component?
Model answer
Resistance is the opposition that a component gives to the current in it.
- 2
What happens to the current in a circuit if the resistance is increased while the potential difference stays the same?
Model answer
The current decreases, because a larger resistance opposes the flow of charge more strongly.
- 3
How is a variable resistor used to dim a lamp?
Model answer
Increasing the resistance of the variable resistor lowers the current in the circuit, so the lamp glows less brightly.
- 4
How does a variable resistor change its resistance?
Model answer
A sliding contact changes the length of resistance wire that the current has to pass through.
- 5
Why is a variable resistor useful when taking a set of current and potential difference readings for a component?
Model answer
Adjusting it changes the current and the potential difference, so several different pairs of readings can be obtained.
- 6
What unit is resistance measured in, and what is its symbol?
Model answer
Resistance is measured in ohms, symbol Ω.
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