Answers to AQA GCSE Electromagnetic Circuit Diagrams (Physics)

Practice Question

1.Explain how a scrap yard crane works to be able to pick up and drop scrap iron.

When the crane operator pushes a switch to complete the circuit, current flows through solenoid and an electromagnet is formed. This allows the crane to pick up scrap metal. 

The metal is then moved to a new location. Crane operator pulls the switch to break the circuit, so current stops flowing, solenoid demagnetises. The crane drops scrap iron.

2. Below is a circuit diagram of an electromagnetic lock. Suggest how it works to unlock the door

When the switch is closed a current flows through the coil, a magnetic field forms around the solenoid and an electromagnet forms. This will cause the yellow metal lock to be pulled to the left to unlock the door.

3. Explain how a relay can be used to switch on a larger circuit using a smaller circuit.

When the switch is closed in the circuit below, the circuit on right is complete, current flows through the coil and a magnetic field forms around solenoid. The newly formed electromagnet attracts the iron armature down. 

The iron armature is on a pivot, so as its pulled downwards, the bottom part moves to the left to push the contacts together on the motor circuit. The motor circuit is now complete so the motor will start.