9.02 Magnetic Fields Flashcards
What does the magnetic field around a magnet do?
Exerts a force on any magnetic material in the field.
The forces come from the poles of the magnet.
In a compass, what does its needle act as and what does it do?
It acts as a tiny magnet which is free to turn.
When near a magnet the needle is turned be the forces between its poles (the needle) and the poles of the magnets.
The needle comes to rest as the Turning effect is zero.
A magnet has a _____ &______ seeking poles.
North
South
Name some properties of the magnetic field lines of a magnet.
- The field lines run from N pole to S pole of a magnet. The field direction MUST be shown by and arrowhead. (It is defined as the direction in which the force on a N pole would act. It is The direction in which the N end of Compass needle would point since it is THE SAME (North and north) so the repeal each other that’s why it points in the same direction. Imagine it as u think about.)
- The magnetic field is strong where the field lines are CLOSEST together.
When 2 magnets are placed near each other what happens to the field lines?
The magnetic field combine to produce a single field.
What is a neutral point?
The field from one magnets exactly cancels (matches) the field from the other, so there is no force on anything at the point, the force is zero.
When do you get a neutral point?
When do you get an almost uniform in strength combined fields?
- When the poles are the same, so the magnetic field repel each other, (see pg203)
- When the poles are opposite, so the magnetic field goes from the N pole to the S pole. The strength of the field is even.
How is the field around the Earth like?
It is like the field around a bar magnet.
Large but ver weak in the case of earth
When there are no other forces how does a compasses needle act?
The N end of the NEEDLE points north. BUT the N pole is always attracted to the S pole(since they are opposite).
This means the earths magnetic S pole must be the north. So that the N pole would be attracted to it. (The north)
It is in Canada called the magnetic north.
Why is the Earths geographic North Pole not match the magnetic north?
Because the earths magnetic axis is not in line with its north-south axis of rotation. (Remember when a bar magnet is suspended it swings to point NORTH-SOUTH.
When the magnetic field lines are vertical how do the pass through a magnet?
A straight line through the bar magnet from the South Pole to the North straight through the bar magnet.
Why is a compass useless in polar regions?
Because the earths magnetic field lines are vertical so the needle will not spin.
