The motor effect
I can describe the force acting on a current–carrying wire or loop in a uniform magnetic field.
The motor effect
I can describe the force acting on a current–carrying wire or loop in a uniform magnetic field.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- The magnetic field lines around a current-carrying wire are concentric circles
- In a uniform magnetic field, a current carrying wire is forced in one direction
- Fleming’s left–hand rule can be used to predict the direction of movement of a current–carrying wire in a magnetic field
- The force on a current–carrying conductor at right angles to a magnetic field, $$F$$, is found using $$F = B I l$$
- Opposite sides of a conducting coil in a uniform magnetic field are forced to move in opposite directions
Keywords
Uniform magnetic field - has evenly spaced field lines and the strength of the magnetic field is the same everywhere
Fleming’s left-hand rule - indicates the direction a conducting wire is forced to move in a uniform magnetic field
Magnetic flux density, B - is a measure of the strength of a magnetic field
Tesla (T) - is the unit that magnetic flux density is measured in
Common misconception
It is not clear how the magnetic field around a conducting wire interacts with a uniform magnetic field.
Focus on observing and predicting the direction that a conducting wire is forced in by a uniform magnetic field, and openly admit that explaining this in terms of how the magnetic field interact is too challenging to include in the syllabus.
To help you plan your year 11 physics lesson on: The motor effect, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 11 physics lesson on: The motor effect, 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.
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The assessment exit quiz will test your pupils' understanding of the key learning points.
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Explore more key stage 4 physics lessons from the Electromagnetism unit, dive into the full secondary physics curriculum, or learn more about lesson planning.
Licence
Lesson video
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Starter quiz
6 Questions
Exit quiz
6 Questions
first finger -
represents the magnetic field direction
second finger -
represents the direction of the current in the wire
third finger -
is not used in Fleming’s left-hand rule
thumb -
represents the direction of the force on the wire
side P -
An upwards force acts.
side Q -
No force acts.
side R -
A downwards force acts.