A student investigates the magnetic field around a straight vertical wire that passes through a horizontal piece of card.
The diagram shows the setup with no current in the wire:
When a strong current flows through the wire from X to Y, a magnetic field is created around the wire that is much stronger than the Earth's magnetic field.
Which of the following shows the correct direction of the compass needle when the current flows downwards from X to Y?
The compass needle points towards the top of the page.
The compass needle points towards the right of the page.
The compass needle points towards the bottom of the page.
The compass needle points towards the left of the page.