A student passes a thick straight wire vertically through the centre of a flat, horizontal card. A current is passed through the wire in an upwards direction.
Describe the shape of the magnetic field lines formed on the card, and state whether their direction is clockwise or anticlockwise when viewed from directly above the card.
Describe how the student can use a plotting compass to map a complete magnetic field line on the card.
An electromagnetic circuit breaker is used to protect a circuit from damage if the current becomes too large, as shown in the diagram below.
The list below contains statements describing how the circuit breaker operates when the current becomes too large. Place them in the correct sequence from 1 to 6:
State the correct sequence of letters in order.
Explain why the contacts do not automatically close again once the current stops flowing.
