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Homework 6: Magnets
(Graph paper required)
1. Shown below is a bar magnet.
a) Redraw the bar magnet to show the magnetic field lines
around it. Include arrows to show their direction.
b) Where is the magnetic field strongest in your diagram?
c) What happens to the strength of the magnetic field as the
distance from the magnet increases?
2.
a) Name two metals that are attracted by a magnet.
b) Name two metals that are not attracted by a magnet.
3. Two magnetic north poles repel each other.
Explain why the north pole of a magnet points to the Earth’s
North Pole.
(Clue – find out if the “North Pole” of the Earth is actually the
north pole of a magnet or not! )
4. The diagram below shows an electromagnet with a variable
resistor in the circuit to vary the current flowing through it.
An ammeter is included to measure the current.
A large compass has its needle deflected by the electromagnet.
The angle of deflection is measured for different currents.
Current (A)
Angle (⁰)
0
0
0.2
40
0.4
60
0.6
70
0.8
75
1.0
78
a) Using graph paper or an ICT package, plot a line graph of
these results.
b) How does increasing the current affect the deflection of the
compass needle?
5. The magnetic field strength of an electromagnet is affected by the
current in its coils.
State two other factors that affect the magnetic field strength of
an electromagnet.
6. Name and describe a use for a permanent magnet.
7. A large electromagnet can be used to lift iron in a scrap yard.
Explain why a permanent magnet is not suitable.
8. Describe a use for a super magnet.