OCR A-Level Physics A H556
Practical Skills in the Written Papers
The Practical Endorsement
Physical Quantities and Units
Making Measurements and Analysing Data
Nature of Quantities
Motion
Forces in Action
Work, Energy and Power
Materials
Newton’s Laws of Motion and Momentum
Charge and Current
Energy, Power and Resistance
Electrical Circuits
Waves
Quantum Physics
Thermal Physics
Oscillations
Gravitational Fields
Astrophysics and Cosmology
Capacitors
Electric Fields
Electromagnetism
Nuclear and Particle Physics
Charge and Current
Elementary charge, charge carriers and Kirchhoff's first law
- 3 things to know
- Papers 2 and 3
Overview
Recall questions on the elementary charge and quantisation of charge, charge carriers in metals and electrolytes, conventional current and electron flow, and Kirchhoff's first law as conservation of charge.
What you need to know
Answer each one before you reveal it.
What charge does an electron carry?
What charge does a proton carry?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is the value of the elementary charge e?
Model answer
1.6 × 10⁻¹⁹ C
- 2
What charge does an electron carry?
Model answer
An electron carries a charge of −e (negative elementary charge).
- 3
What charge does a proton carry?
Model answer
A proton carries a charge of +e (positive elementary charge).
- 4
What does it mean for electric charge to be quantised?
Model answer
Net charge on a particle or object can only exist as integer multiples of the elementary charge e.
- 5
Why can an object never have a charge of 2.4 × 10⁻¹⁹ C?
Model answer
Because charge is quantised and can only exist as integer multiples of e (1.6 × 10⁻¹⁹ C), and 2.4 × 10⁻¹⁹ C is not an integer multiple of e.
- 6
What causes electric current in metals?
Model answer
Electric current in metals is due to the movement of free electrons.
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