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physics Physics For High Schools (KS4)

Solved problems for the chapter:

Induced Magnetism

View the theory »

Magnetic Induction

1. Magnetic flux

2. Faraday's law of induction

3. Self induction

4. Direction of induced voltage

5. Forum

↓ Show theory [1] ↓

Detailed solution steps are available at:

https://en.openprof.com/wb/chapter:induced_magnetism/3623/

Example 1.

An unmagnetised piece of soft iron is placed close to a strong permanent magnet, as shown below.

What is the induced polarity of end X of the soft iron and in which direction does the magnetic force act on the soft iron?

	polarity of end X	direction of force on the soft iron
A	N	to the left
B	N	to the right
C	S	to the left
D	S	to the right

Example 2.

The diagram shows a bar magnet at rest on a smooth horizontal surface. A length of soft-iron wire is held parallel to the magnet.

The wire is released. What happens?

The wire moves away from the magnet.
The wire moves towards the magnet.
The wire’s centre stays in its present position and the wire rotates through 90° in a clockwise direction.
The wire’s centre stays in its present position and the wire rotates through 90° in an anticlockwise direction.

A student investigate which end of a magnetic compass needle is attracted to a bar magnet.

What does the investigation show?

Both ends of the compass needle are attracted by the north pole of the magnet.
Both ends of the compass needle are attracted by the south pole of the magnet.
One end of the compass needle is attracted by the north pole and the other end by the south pole.
The compass needle is not attracted by either end of the magnet.

Two metal rods each have a painted end. The painted ends are placed next to the N pole and S pole of the bar magnet in turn.

The rods are made from iron, aluminum, or magnetised steel.

rod	placed next to	observation
1	N pole of bar magnet	attracts
1	S pole of bar magnet	attracts
2	N pole of bar magnet	nothing happens
2	S pole of bar magnet	nothing happens

What are rod 1 and rod 2 made from?

	rod 1	rod 2
A	magnetised steel	aluminum
B	iron	magnetised steel
C	aluminum	iron
D	iron	aluminium

A soft iron bar is not magnetized. It is held close to the N pole of a magnet and then close to the S pole of the same magnet. What will be the result?

	N pole	S pole
A	attract	attract
B	attract	repel
C	repel	attract
D	repel	repel

The ends of three metal rods are tested by holding end Q of rod 1 close to the other rods.

The results are as follows:

End Q:

attracts end R
attracts end S
attracts end T
repels end U

Which of the metal rods is a magnet?

rod 1 only
rod 1 and 2 only
rod 1 and 3 only
rod 3 only

A magnet is dropped vertically through a solenoid. This induces magnetic poles at both ends of the solenoid.

Which magnetic poles are induced at position X in diagram 1 and diagram 3?.

	diagram 1	diagram 3
A	N pole	N pole
B	N pole	S pole
C	S pole	N pole
D	S pole	S pole

A metal rod XY is placed near a magnet. End X is attracted when it is placed near to the north pole of the magnet and also when it is placed near to the south pole.

How does end Y behave when it is placed, in turn, near to the poles of the magnet?

	Y near north pole	Y near south pole
A	attraction	attraction
B	attraction	repulsion
C	repulsion	attraction
D	repulsion	repulsion

An iron ball on a horizontal wooden table rolls near the north pole of a bar magnet which is lying on the table. Which diagram shows the most likely path of the ball, as seen from above the table?

10.

A bar magnet picks up two steel bolts. Which diagram shows the magnetic poles induced in the bolts?

11.

Small particles of metal are scattered near a bar magnet to show the pattern of the magnetic field.

Which metal is suitable?

Aluminium
Brass
Copper
Iron

12.

The north pole of a bar magnet is placed next to the end P of an iron bar PQ. Magnetic poles are induced in the iron bar.

What are the magnetic poles induced at P and at Q?

	magnetic pole at P	Magnetic pole at Q
A	north	north
B	north	south
C	south	north
D	south	south

13.

A bar magnet is brought near to a rod with unknown material. The unknown rod is attracted to both ends of the bar magnet.

Which material is the rod made from?

aluminum
magnetised steel
unmagnetized iron
plastic

14.

A horseshoe magnet is brought near to an unmagnetised iron bar.

Which row in the table shows the magnetic poles induced in the iron bar and the direction of the forces between the bar and the magnet?

15.

A permanent magnet is placed close to a bar of soft iron PQ.

What happens?

P becomes a north pole
P becomes a south pole
PQ does not become magnetized
The poles of the magnet are reversed

16.

A chain of steel nails and a chain of iron nails hang from a strong magnet. The chains are then carefully removed from the magnet.

What happens to the chains?

both chains fall apart
both chains stay together
only the chain of iron nails fall apart
only the chain of steel nails fall apart

17.

A magnet attracts two poles of iron.

What is the arrangement of the induced poles in the pieces of iron?

18.

Two bars of soft iron are placed near a bar magnet.

Which row states and explains the behaviour of poles P and Q of the soft iron bars?

	P and Q	Reason
A	attract	P and Q are like poles
B	attract	P and Q are unlike poles
C	repel	P and Q are like poles
D	repel	P and Q are unlike poles

19.

In two separate experiments, a magnet is brought near an unmagnetised iron bar. This causes the bar to become magnetized.

Which magnetic poles are induced at X and at Y?

	Pole induced at X	Pole induced at Y
A	N	N
B	N	S
C	S	N
D	S	S

20.

The N pole of a magnet repels one end of bar X.

What happens when the other end of bar X is placed near to the poles of the magnet?

	Other end near N pole	Other end near S pole
A	attract	attract
B	attract	repel
C	repel	attract
D	repel	repel