An automatic circuit breaker safety switch uses an electromagnetic solenoid mechanism to trip a circuit when an overload occurs. When activated, the solenoid pulls a cylindrical armature against a tension spring to separate the contacts and interrupt the current flow, as shown below.
Explain why the armature must be constructed from soft iron rather than aluminum.
When the solenoid is energized, a magnetic force of 5.25 N is applied to the armature, pulling it and stretching the tension spring by 1.50 cm. Calculate the spring constant of the tension spring in N/m\text{N/m}N/m.
State two modifications to the solenoid or its electrical circuit that would increase the magnetic force acting on the armature.
The motor effect Questions
Practise AQA GCSE Physics The motor effect with exam-style questions for Foundation and Higher tier. 25 questions covering Electromagnetism, Fleming's left-hand rule (HT only), Electric motors (HT only), and Loudspeakers (physics only) (HT only), matched to the AQA GCSE Physics (8463) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.