OCR A-Level Physics B H557
Planning
Implementing
Analysis
Evaluation
Practical Skills
Use of Apparatus and Techniques
Fundamental Data Analysis
Imaging and Signalling
Sensing
Mechanical Properties of Materials
Waves and Quantum Behaviour
Space, Time and Motion
Creating Models
Out Into Space
Our Place in the Universe
Matter: Very Simple
Matter: Hot or Cold
Electromagnetism
Charge and Field
Probing Deep Into Matter
Ionising Radiation and Risk
Sensing
Potential difference, e.m.f. and energy transfer
- 3 things to know
- Components 01, 02 and 03
Overview
Recall questions on defining potential difference, the volt and e.m.f., the difference between e.m.f. and potential difference, energy transferred per coulomb, and why a voltmeter must have a very high resistance.
What you need to know
Answer each one before you reveal it.
State the relationship for potential difference in terms of work and charge.
Define the volt.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Define potential difference.
Model answer
Potential difference is the energy transferred from the circuit per unit charge passing between two points.
- 2
State the relationship for potential difference in terms of work and charge.
Model answer
V = W/Q, in volts when the work is in joules and the charge in coulombs.
- 3
Define the volt.
Model answer
One volt is one joule per coulomb.
- 4
Define the e.m.f. of a source.
Model answer
The e.m.f. is the energy transferred to the circuit by the source per unit charge passing through it.
- 5
State the difference between e.m.f. and potential difference.
Model answer
E.m.f. is the energy given to each coulomb by the source, while potential difference is the energy given up by each coulomb in part of the circuit.
- 6
Why is the symbol ε used for e.m.f. rather than E?
Model answer
E is already used for energy and for electric field strength, so ε is used to avoid confusion.
Other ways to work this
The same content, four other ways.
What is inside Levo
Six ways to work the same material.
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