11. Navin
sets up an experiment on electromagnets as shown below.
He
recorded his results as shown in the table.
Set-up
|
Number of batteries
|
Number of coils of wire
|
Number of paper clips attracted
|
A
|
1
|
20
|
2
|
B
|
2
|
20
|
5
|
C
|
3
|
20
|
7
|
(a) State the aim of his experiment.
__________________________________________________________________________
(b) Without changing the battery in Set-up A,
suggest another way to increase the number of paper clips to be attracted to
the electromagnet?
__________________________________________________________________________
(c) What is the relationship between the number of
batteries and the strength of the electromagnet?
__________________________________________________________________________
__________________________________________________________________________
12.Maggi placed three blocks of different materials on a
thin piece of cardboard, She then put a bar magnet under the cardboard and
moved the bar magnet to the other end of the cardboard as shown below.
Maggi
noticed that only the steel block moved with the magnet to the other end of the
cardboard
(a) Explain why the plastic and wooden block did not
move.
__________________________________________________________________________
__________________________________________________________________________
(b) The experiment was not a fair test. State what
Maggi should do to ensure a fair test.
__________________________________________________________________________
13. Sam was
given the following materials. - one
wooden ruler - one paper clip - 2 bar magnets T and U
He was told to use all the above materials to find out
which magnet T or U has greater magnetic strength. Sam recorded his procedure
in the table below. Steps 1,2,4 and 5 had been written for you. Write down
steps 3 and 6 which he need to conduct to complete his experiment.
Steps
|
Actions
|
1
|
Place magnet T next to the ruler.
|
2
|
Place a paper clip along the ruler
about 20cm away from the magnet.
|
3
|
(a) ______________
|
4
|
Measure maximum distance between
magnet and clip that still allows clips to be attracted.
|
5
|
Repeat steps 1-4 for magnet T to
get reliable results.
|
6
|
(b) ____________
|
14. Ben
put three ring magnets through a vertical wooden rod, one above the other. He
observed that magnet 2 rested on top of magnet 1 while magnet 3 'floated' above
magnet 2.
(a)
Explain this observation.
(b) What could Ben do such that the three magnets were
attracted to one another?
__________________________________________________________________________
15. Susan placed a magnet near an iron
rod. The iron rod moved towards the magnet.
(a)
Magnet exerts a _______________ on the iron rod.
(b) Choose the correct word from the box to answer the
question below. hard, magnetic,
strong
Susan's observation shows that iron is a
_______________ material
16. A steel bar was magnetised using the
'stroke' method as shown in Diagram 1 below.
Diagram 2 shows the magnetic poles of the steel bar after it was magnetised.
Two magnets were used to stroke
another steel bar as shown in Diagram 3 below. Identify the poles of the
magnetized steel bar at X and Y respectively.
17. Sally
placed pins, one at a time, at part A, B and C of a bar magnet until no more
pins could be attracted by it. She observed the following result shown in
Figure 1.
What
can Sally conclude about the magnetic strength of the bar magnet based on the
diagram.
18. Joanne was given two similar
metal rods J and K. One of the rods was a magnet and the other was a magnetic object.
She wanted to find out which rod was the magnet. Joanne arranged the rods J and K
as shown in Figure 2. She found that there was a strong magnetic pull between
the rods. When she re-arranged the rods as shown in Figure 3, the magnetic pull
between them as weak.
Which
rod J or K is the magnet? Give a reason for your answer.
__________________________________________________________________________
19. Simon conducted an experiment to
find out about magnetism in a science laboratory as shown below. The diagrams
below showed the results of the experiment that he has observed.
When Simon went home, he noticed that his mother left a piece of paper note on
the door of the refrigerator. The note was held fast onto the door with the
help of a magnet as shown below.
(a) Name a material that the door of the refrigerator is
most likely made of.
__________________________________________________________________________
(b) Give a reason why the magnet was able to hold a piece of
paper on the door of the refrigerator.
__________________________________________________________________________
20. Jessica
was given a large glass bowl containing a mixture of Styrofoam balls, iron
nails and pebbles as shown below. She was given a fish net, a magnet, a stirrer
and 500ml of water. She was then asked to separate all the three items in the
glass bowl. The four statements below describes what Jessica could do to
separate the items
Read the statements carefully and arrange them in the
correct order that Jessica should follow to separate the three items.
A - Pour away the water leaving behind only the pebbles.
B - Scoop up the floating Styrofoam balls with the fish net.
C - Pour water into the mixture and stir the mixture with the stirrer.
D - Remove all the iron nails by using a magnet to attract them.
