01 Magnetism

Question 1

Name the 3 magnetic elements:

Answer 1

Iron; Nickel; cobalt

Question 2

What are the ends of a bar magnet called?

Answer 2

North pole and south pole

Question 3

In which region around a bar magnet is the magnetic field the strongest? How can the magnetic field lines indicate this?

Answer 3

The magnetic field is strongest at the poles, the field lines are close together at the poles indicating a stronger field.

Question 4

How can you create a uniform field using two bar magnets? [3 points]

Answer 4

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

Question 5

Describe the magnetic field created when the N-pole of one bar magnet is near the S-pole of another. [2 points]

Answer 5

Uniform field

Magnetic field lines are parallel AND evenly spaced

Question 6

Define magnetic field:

Answer 6

A region of space where a magnetic material experiences a force.

Question 7

Exaplain how to plot a magnetic field line with a compass and a bar magnet. [5 points]

Answer 7

1. Draw around magnet after placing on paper
2. Draw dot close to magnet
3. Place tail of plotting compass on dot.
4. Draw dot where the north arrow points on plotting compass, from North to South
5. Repeat steps 3-4 (until you can see the shape of the magnetic field around Bar magnet)

Question 8

Give the name of a magnetically soft metal

Answer 8

iron

Question 9

Give the name of a magnetically hard metal

Answer 9

steel

Question 10

What is the point called between two adjacent N-poles of a magnet where their magnetic field cancels?

Answer 10

Neutral point

Question 11

What is the law of magnetism? [2 points]

Answer 11

Like poles repel

Unlike poles attract

Question 12

What is a permanent magnet made of? Magnetically hard material or magnetically soft?

Answer 12

Magnetically hard- so that it does not lose its magnetism easily

Question 13

How can you observe the shape of a magnetic field around a magnet?

Answer 13

1. Place paper over top the magnet
2. Sprinkle iron filings on the paper
3. Tap the paper to help the iron filings line up in the field

Question 14

What happens when an iron nail is brought near the N Pole of a magnet. [3/4points]

Answer 14

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.

Question 15

Define magnetic field:

Answer 15

the region where a magnetic force is felt

Question 16

like poles…

Answer 16

repel

Question 17

opposite poles…

Answer 17

attract

Question 18

Where are magnetic fields strangest at and why?

Answer 18

poles because the field lines are close together

Question 19

RP: Give the 6 steps required to plot a magnetic field with a compass.

Answer 19

1. Draw around magnetic after placing on paper
2. Draw dot close to magnet
3. Place tail of plotting compass on dot
4. Draw dot where North arrow points on plotting compass
5. Repeat steps 3-4 until you can see the shape of the magnetic field around the Bar magnet
6. join up the dots.

Question 20

Give 2 properties of a magnetically soft metal:

Answer 20

low coercivity
loses magnetation easily

Question 21

give an example of a magnetically soft metal:

Answer 21

iron

Question 22

give 2 properties of a magnetically hard metal:

Answer 22

high coercivity
retains magnetisation

Question 23

give an example of a magnetically hard metal:

Answer 23

steel

Question 24

Give the method used with iron filings to see the shape of a magnetic field [3 points]

Answer 24

1. place sheet of paper over a/2 bar magnet(s)
2. Srpinkle (a generous) amount of iron filings onto the page
3. tap the paper gently until you can visualise the field.

Question 25

Give the disadvantage of using the iron filings method instead of a compass to plot the magnetic field.

Answer 25

there is no way to tell apart the poles - no way of telling N from S

Question 26

true or false: in a magnet, the domains are dealigned.

Answer 26

FALSE. in a magnet, the domains are align.

Question 27

give the formation of the domains in a magnetised metal:

Answer 27

lined up.

Question 28

give the formation of the domains in a demagnetised metal:

Answer 28

randomly arranged

Question 29

How would one magnetise an iron nail with a bar magnet? (and how does this affect the domains inside)

Answer 29

stroke the iron nail with a magnet for several minutes (this aligns the domains)

Question 30

give 1 way to demagnetise a permanent magnet:

Answer 30

aotf: heat it hammer it drop it (this dealigns the domains)

Question 31

what is the explanation of a saturated magnet? [2 points]

Answer 31

when 'all' the domains in a magnetic material are aligned and can't get any stronger