Magnetic field of magnets. Warm-up. 1 Three ring magnets are inserted into a vertical rod on a wooden stand. Which of the following results is/are reasonable?. Red & blue sides denote the 2 poles of a magnet. C. A. B. Warm-up.
1 Three ring magnets are inserted into a vertical rod on a wooden stand. Which of the following results is/are reasonable?
Red & blue sides denote the 2 poles of a magnet.
2 4 objects in bar shape are wrapped with paper so that they look the same.
2 of them are bar magnets, 1 is an iron bar & 1 is a copper bar. Without using any other tools, how can you identify all of them?
Paper clips are attracted to bar magnets.
The magnetic force seems to come from 2 ends.
How are they called?
it swings until it lies pointing north-south.
north pole (N-pole)
south pole (S-pole)
If 2 bar magnets are brought together…
unlike poles attract
like poles repel
Like poles repel each other;
unlike poles attract each other.
Magnetic fields of permanent magnets
Investigate the magnetic fields produced by permanent magnets.
2 slab-shaped magnets on steel yoke
bar magnet on underside of perspex board
Iron filings are attracted by magnet, settle into a special pattern.
These patterns show the magnetic fieldsof the magnets.
Field lines run from the N-pole round to theS-pole.
field lines between unlike poles
field lines between like poles
Neutral point: the field from one magnet cancels the field from another (No magnetic field exists)
What is its magnetic
uniform magnetic field
geographic North Pole
magnetic South Pole
The earth has a weak magnetic field.
Note: N-pole of compass needle points north
S-pole of the 'earth magnet' is actually in the north!
2 bar magnets placed side by side with like poles facing each other.
(a) Mark in the diagram the positions of all neutral points.
(b) Explain briefly why there are neutral points in these positions.
At P, the magnetic field due to the 2 N-poles & the 2 S-poles cancel each other out.
The same explanation applies to the neutral point at Q.
(c) What happens when a plotting compass is put in these positions?
The magnetic field at P and Q is zero. The needle of the compass will lie in whatever direction it settles down to.
In which direction does a magnet point if it is hung freely at the North Pole?
A The N-pole of the magnet points downwards.
B The S-pole of the magnet points downwards.
C The S-pole of the magnet points horizontally.
D Any direction.
True or false: Every magnet has a north pole and a south pole, just as every coin has 2 sides, a 'head' & a 'tail'. If you break a magnet into 2, you get 2 smaller magnets, each again having both a north pole & a south pole.
Using iron filings, we may be able to figure out the __________ and the ___________, but not the __________ of a magnetic field in a region. (strength/direction/pattern)
In a region where a magnetic field is uniform, the field lines must be _________ (convergent/parallel/divergent) and __________ (evenly/unevenly) spaced.
Draw a uniform magnetic field in the box.
A strong magnet attracts a paper clip with a certain force.
(a) Does the paper clip exert a force on the magnet? (Yes/No)
(b) If no, why not? If yes, does it exert as much force on the magnet as the magnet exerts on it? Why?
Yes, because they are an action-reaction pair.