01 Magnetism - 3rd Form Flashcards
What are the ends of a bar magnet called?
north pole and south pole
In which region around a bar magnet is the magnetic field the strongest? How can the magnetic field lines indicate this?
The magnetic field is strongest at the poles, the field lines are close together at the poles indicating a stronger field.
How can you create a uniform field using two bar magnets?
Place the bar magnets so that the N pole of one magnet is facing the S pole of the other.
Move them so that they are close but not touching
There is a uniform field between the poles
Describe the magnetic field created when the N-pole of one bar magnet is near the S-pole of another.
Uniform field
Magnetic field lines are parallel AND evenly spaced
What is a magnetic field?
A region of space where a magnetic material experiences a force.
Name a metal which is magnetically hard.
Steel
Name a metal which is magnetically soft
iron
What is the point called between two adjacent N-poles of a magnet where their magnetic field cancels?
neutral point
What is the law of magnetism?
Like poles repel
Unlike poles attract
What is the difference between the domains in a magnetically hard material and a magnetically soft material?
Magnetically hard- difficult for domains to align in a field (also difficult for domains which are lined up to de-align)
Magnetically soft- easy for domains to align in a magnetic field and then de-align when field is removed.
What is a permanent magnet made of? Magnetically hard material or magnetically soft?
Magnetically hard- so that it does not lose its magnetism easily
How can you observe THE SHAPE of a magnetic field around a magnet?
- Pace paper over top the magnet
- Sprinkle iron filings on the paper
- Tap the paper to help the iron filings line up in the field
What happens when an iron nail is brought near the N Pole of a magnet.
The nail is attracted to the N-pole
The domains in the iron nail line up (point away) in the field creating a S-pole at the top of the nail closest to the magnet. (Magnetism is induced in the iron nail)
Opposite poles attract and the nail sticks to the magnet.
What is the difference in the orientation of the domains in a magnetised and demagnetised material?
Magnetised- domains are lined up
De-magnetised- domains are randomly arranged
How can you show the shape AND direction of a magnetic field around a magnet?
- place a magnet on a piece of paper
- place a plotting compass at one corner of the N-pole of the magnet
- draw a dot where the compass is pointing.
- move the compass forward so that the tail is adjacent to the point you just plotted
- draw another dot where the compass is pointing
- Continue this until you reach the S-pole and connect the dots with a smooth curve.
- Repeat steps 3-6 drawing multiple field line around the magnet
Draw an attracting field between a North and South pole.
Draw a repelling field between two N-poles
How can an iron nail be magnetised?
Stroke the iron nail with a magnet for several minutes.
This will align the domains in the iron nail and magnetise it.
How can you demagnetise a permanent magnet?
Heat it, hammer it or drop it repeatedly.
This will de-align the domains (demagnetise it)
In which direction do magnetic field lines run?
North to South
OUT of the North
INTO the South
What do we call it when ‘all’ the domains in a magnetic material are aligned and magnet cannot become any stronger?
saturated
