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GCSE Standard Questions: The Motor Effect

Q3. When a conductor carrying an electric current is placed in a magnetic field a force may act on it.

(a) State two ways in which this force can be increased.

Increase the current (or credit 'increase the p.d./voltage' or 'reduce the resistance' or 'have thicker wiring' or 'add extra / more cells' – as those would increase the current!)

Increase the magnetic field (strength) or credit 'have stronger magnet(s)' but do not credit 'bigger' magnets as size does not necessarily relate to strength.

(2 marks)

(b) State two ways in which this force can be made to act in the opposite direction.

Reverse polarity or connect the battery the other way round Reverse direction of the magnetic field or put the magnet the other way round/ reverse the magnet

(2 marks)

(c) In what circumstance will no force act on a conductor carrying an electric current and in a magnetic field?

There will be no force if the conductor is parallel to the magnetic field OR the lines of magnetic force and path of current flow do not cross.

(1 mark)

(Total 5 marks)