4.7.2
Resistance
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Resistance
Resistance is a measure of how difficult it is for current to flow through a component.

Charge flow
- When charge flows in an electric circuit, the size of the current is affected by two things:
- The resistance: If the resistance is increased, the current will decrease.
- The potential difference: If the potential difference is increased the current will increase.

Units - Ohms
- Resistance is measured in ohms, Ω.
Measuring Resistance
We calculate the resistance using R = Δ V/I. We calculate potential difference using a voltmeter and current using an ammeter at the same time.
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Potential difference across a component
- To measure the resistance of a component (e.g. lamp or resistor), measure the potential difference across the component.
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Current through a component
- Use an ammeter to measure the current flowing through a component.
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Resistance
- The longer the wire, the higher the resistance.
1Space, Time & Motion
1.1Motion
1.2Forces
1.3Momentum & Impulse
2The Particulate Nature of Matter
2.1Thermal Concepts
3Wave Behaviour
3.1Oscillations
3.2Travelling Waves
3.3Wave Characteristics
3.4Wave Behaviour
3.5Standing Waves
3.6Simple Harmonic Motion
3.7Single Slit Diffraction
3.8Interference
3.9Doppler Effect
4Fields
4.1Circular Motion
4.2Newton's Law of Gravitation
4.3Fields
4.4Fields at Work
4.5Electric Fields
4.6Magnetic Effect of Electric Currents
4.7Heating Effect of Currents
4.8Electromagnetic Induction
4.9Power Generation & Transmission
5Nuclear & Quantum Physics
5.1Discrete Energy & Radioactivity
5.2Nuclear Reactions
5.3The Interaction of Matter with Radiation
6Measurements
6.1Measurements & Errors
6.2Uncertainties & Errors
6.3Vectors & Scalars
Jump to other topics
1Space, Time & Motion
1.1Motion
1.2Forces
1.3Momentum & Impulse
2The Particulate Nature of Matter
2.1Thermal Concepts
3Wave Behaviour
3.1Oscillations
3.2Travelling Waves
3.3Wave Characteristics
3.4Wave Behaviour
3.5Standing Waves
3.6Simple Harmonic Motion
3.7Single Slit Diffraction
3.8Interference
3.9Doppler Effect
4Fields
4.1Circular Motion
4.2Newton's Law of Gravitation
4.3Fields
4.4Fields at Work
4.5Electric Fields
4.6Magnetic Effect of Electric Currents
4.7Heating Effect of Currents
4.8Electromagnetic Induction
4.9Power Generation & Transmission
5Nuclear & Quantum Physics
5.1Discrete Energy & Radioactivity
5.2Nuclear Reactions
5.3The Interaction of Matter with Radiation
6Measurements
6.1Measurements & Errors
6.2Uncertainties & Errors
6.3Vectors & Scalars
Practice questions on Resistance
Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.
- 1Resistance is a measure of the...Multiple choice
- 2An electric current will increase when:True / false
- 3Which variables affect the size of a current?Fill in the list
- 4
- 5To measure the resistance you need:True / false
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