Simple Magnetism and Magnetic Fields
Chapter 19 MCQs
For Full Scale Course: Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total Personal A Grades, 11 World Records and 7 Distinctions, Educate A Change.
1
A bar magnet is suspended freely by a thread and comes to rest.
Which statement is correct?
A its north-seeking pole points approximately towards geographic south
B its north-seeking pole points approximately towards geographic north
C both poles point east-west
D it stops in a random direction because magnets have no preferred direction
2
A student places a plotting compass near the north pole of a bar magnet.
Which direction does the north end of the compass needle point?
A towards the north pole of the magnet
B away from the north pole of the magnet
C perpendicular to the magnetic field
D towards the centre of the magnet only
3
Two bar magnets are placed near each other. The north pole of one magnet is brought near the south pole of the other.
What happens?
A they repel
B they attract
C there is no force
D they first repel, then attract
4
Two unknown poles of two magnets repel each other.
What can definitely be concluded?
A both are north poles
B both are south poles
C the poles are unlike
D the poles are like
5
A pole of a magnet attracts an unknown object.
What can definitely be concluded about the unknown object?
A it is the opposite pole of another magnet
B it is an unmagnetised magnetic material
C it is either an opposite magnetic pole or a magnetic material
D it is a non-magnetic material
6
A student wants to test whether a metal rod is a magnet or just a piece of iron.
Which observation proves that the rod is a magnet?
A it is attracted by a known magnet
B it attracts paper clips
C it repels one pole of a known magnet
D it becomes warm when rubbed
7
Why is repulsion the only sure test for magnetism?
A attraction happens only between two magnets
B repulsion happens between a magnet and soft iron
C attraction can occur between a magnet and an unmagnetised magnetic material
D repulsion happens between any two metals
8
A bar magnet is broken into two equal pieces.
Which statement is correct?
A each piece has only one pole
B one piece has two north poles and the other has two south poles
C each piece becomes a smaller magnet with a north pole and a south pole
D both pieces become unmagnetised immediately
9
Which material is most suitable for making a permanent magnet?
A soft iron
B steel
C copper
D aluminium
10
Which material is most suitable for making the core of an electromagnet?
A steel because it is hard to magnetise and demagnetise
B soft iron because it is easily magnetised and demagnetised
C copper because it is non-magnetic
D aluminium because it repels magnets strongly
For Full Scale Course: Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total Personal A Grades, 11 World Records and 7 Distinctions, Educate A Change.
11
A steel needle is stroked several times in the same direction with one pole of a strong magnet.
What is the purpose of this process?
A to demagnetise the needle
B to magnetise the needle
C to make the needle non-magnetic
D to make the needle lose mass
12
Which method can demagnetise a steel magnet?
A place it in a plastic bag
B stroke it repeatedly in one direction with a magnet
C heat it strongly and allow it to cool away from a magnetic field
D place it near copper
13
A magnet is hammered repeatedly.
What is the most likely effect?
A it becomes more strongly magnetised
B it may become demagnetised
C its north pole changes into a south pole only
D it becomes electrically charged
14
A magnet is placed inside a coil carrying alternating current.
What is the likely effect if the current is gradually reduced to zero?
A the magnet is strengthened
B the magnet is demagnetised
C the magnet becomes radioactive
D only the north pole disappears
15
Which statement about magnetic field lines around a bar magnet is correct?
A they cross each other near the poles
B they point from south to north outside the magnet
C they point from north to south outside the magnet
D they exist only inside the magnet
16
Where is the magnetic field around a bar magnet strongest?
A halfway between the poles
B near the poles
C far away from the magnet
D at the exact centre only
17
A diagram shows magnetic field lines close together near one end of a magnet.
What does this show?
A the magnetic field is stronger there
B the magnetic field is weaker there
C the magnet is not magnetised there
D field direction is impossible to determine
18
A plotting compass is placed at different points around a bar magnet.
What does the compass needle show?
A the direction of the magnetic field at that point
B the strength of gravity at that point
C the direction of electric current in the magnet
D the speed of the magnet
19
Which statement about magnetic field lines is correct?
A they show the path followed by magnetic material particles
B they show the direction of force on a north pole
C they show the direction of force on a south pole
D they always point towards a north pole outside the magnet
20
A small plotting compass is placed exactly on the neutral point between two identical bar magnets arranged with like poles facing each other.
What is true at the neutral point?
A magnetic field strength is zero
B compass needle spins at maximum speed
C magnetic field is strongest
D only gravitational force acts on the compass
21
Two identical bar magnets are placed with their north poles facing each other.
What happens to the magnetic field at the midpoint between the two north poles?
A the fields reinforce in the same direction
B the fields cancel, producing a neutral point
C the field becomes equal to Earth’s gravitational field
D the field lines cross each other
22
Two identical bar magnets are placed with the north pole of one facing the south pole of the other.
What happens to the magnetic field in the gap between them?
A field lines go from north to south and the field is strengthened
B field lines go from south to north and the field disappears
C field lines cross at the centre
D no magnetic force acts in the gap
23
A magnetic field pattern shows lines leaving pole X and entering pole Y.
Which statement is correct?
A X is a south pole and Y is a north pole
B X is a north pole and Y is a south pole
C both X and Y are north poles
D both X and Y are south poles
24
A student sprinkles iron filings around a bar magnet.
Why do the filings form a pattern?
A each filing becomes induced as a tiny magnet and aligns with the magnetic field
B the filings are pushed away from all magnetic field lines
C the filings become electrically charged and repel each other only
D the magnet melts the filings slightly
25
Why should a plotting compass not be placed too close to a strong magnet for ordinary field plotting?
A the compass needle may be strongly affected and not show the wider field pattern clearly
B magnetic fields cannot exist near poles
C the compass turns into plastic
D the magnet becomes demagnetised immediately
For Full Scale Course: Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total Personal A Grades, 11 World Records and 7 Distinctions, Educate A Change.
26
A piece of soft iron is brought near the north pole of a strong bar magnet.
Which pole is induced at the end of the soft iron nearest the magnet?
A north pole
B south pole
C no pole
D both north and south poles at the same end
27
A piece of soft iron is attracted to either pole of a magnet.
Why?
A the nearby end of the iron is induced with the opposite pole
B the nearby end is always induced as a north pole
C soft iron is always a permanent magnet
D soft iron repels both poles equally
28
A magnet attracts an unmagnetised iron nail. The nail then attracts another nail.
What is the best explanation?
A the first nail becomes magnetised by induction
B the first nail becomes a permanent magnet forever
C the first nail becomes non-magnetic
D the second nail repels the first nail
29
A chain of iron nails hangs from a magnet. When the magnet is removed, most nails fall off.
What does this show?
A iron is not magnetic at all
B iron keeps strong magnetism permanently
C iron is easily magnetised but loses magnetism easily
D iron becomes copper when magnetised
30
A steel pin is magnetised and then removed from the magnetising field.
Which statement is most likely correct?
A it loses magnetism immediately
B it keeps much of its magnetism
C it becomes non-magnetic because steel cannot be magnetised
D it becomes softer
31
A soft iron rod and a steel rod are both placed inside identical coils carrying the same direct current.
Which row is correct when the current is switched off?
| soft iron rod | steel rod | |
|---|---|---|
| A | loses magnetism easily | retains more magnetism |
| B | retains more magnetism | loses magnetism easily |
| C | both retain magnetism equally | |
| D | neither was magnetised |
32
A magnet is stored with a soft iron keeper across its poles.
Why is the keeper used?
A to help reduce loss of magnetism
B to make the magnet repel Earth’s field
C to turn the magnet into an electromagnet
D to remove both poles permanently
33
A horseshoe magnet has a soft iron keeper placed across its poles.
Which statement best explains the keeper’s effect?
A it completes a magnetic path and helps maintain magnetisation
B it blocks all gravitational forces
C it changes north into south permanently
D it makes the magnet non-magnetic immediately
34
A bar magnet is stored with two soft iron keepers and unlike poles close together.
Which arrangement best preserves magnetism?
A unlike poles connected by keepers
B like poles connected by keepers
C poles left far apart with no keeper
D magnet heated strongly before storage
35
A student places a magnet near a pile containing iron, copper, aluminium and steel pieces.
Which pieces are most likely to be attracted?
A copper and aluminium only
B iron and steel only
C aluminium and steel only
D copper and iron only
36
Which group contains only magnetic materials?
A iron, steel, nickel
B copper, aluminium, brass
C iron, copper, plastic
D nickel, aluminium, glass
37
Which material is not attracted strongly by a magnet?
A iron
B nickel
C steel
D copper
38
A student says, “All metals are magnetic.”
Which correction is best?
A only some metals, such as iron, steel and nickel, are strongly magnetic
B all metals are magnetic if heated
C no metals are magnetic
D only copper is magnetic
39
A magnetic compass is placed near a current-carrying wire. The needle deflects.
What does this show?
A an electric current produces a magnetic field
B a magnetic field produces mass
C the compass has become radioactive
D current can flow only through magnetic materials
40
A wire carries a current vertically upwards. A compass nearby deflects.
What is the shape of the magnetic field around the wire?
A straight lines parallel to the wire
B circles centred on the wire
C radial lines directly away from the wire
D random broken lines
For Full Scale Course: Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total Personal A Grades, 11 World Records and 7 Distinctions, Educate A Change.
41
The current in a straight wire is reversed.
What happens to the magnetic field around the wire?
A direction reverses
B strength becomes zero permanently
C field changes from circular to straight
D field exists only at one end of the wire
42
A current in a straight wire is increased.
What happens to the magnetic field near the wire?
A it becomes weaker
B it becomes stronger
C it changes into an electric field only
D it disappears
43
A compass is moved farther away from a current-carrying straight wire.
What happens to the magnetic effect on the compass?
A it becomes stronger
B it becomes weaker
C it remains exactly the same
D it reverses automatically
44
A long solenoid carries a direct current.
Which statement best describes the magnetic field inside the solenoid?
A weak and irregular
B strong and nearly uniform
C zero everywhere
D circular around each end only
45
Which change increases the magnetic field strength of a solenoid?
A reducing the current
B decreasing the number of turns
C inserting a soft iron core
D replacing soft iron core with copper
46
A solenoid has a soft iron core. The current is switched on.
Why does the core increase the magnetic field strength?
A soft iron becomes magnetised by the field of the solenoid
B soft iron cancels the magnetic field
C soft iron prevents current from flowing
D soft iron is non-magnetic
47
A solenoid is used as an electromagnet.
Which change would reverse the poles of the electromagnet?
A reverse the current direction
B increase the current
C add more turns in the same direction
D use a stronger soft iron core without changing current direction
48
An electromagnet is used in a scrapyard crane.
Why is an electromagnet better than a permanent magnet for this use?
A it can be switched on and off
B it attracts copper but not iron
C it has no magnetic field when current flows
D it works only in a vacuum
49
A relay uses an electromagnet.
What happens when current flows in the relay coil?
A the electromagnet attracts an iron armature and can close another circuit
B the coil becomes a permanent steel magnet forever
C the current destroys the iron armature
D the relay changes AC into DC automatically
50
An electric bell uses an electromagnet and a contact breaker.
Why does the hammer vibrate repeatedly?
A the circuit repeatedly makes and breaks, switching the electromagnet on and off
B the hammer is a permanent magnet that spins continuously
C the bell works only because of thermal expansion
D the electromagnet repels copper contacts only
For Full Scale Course: Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total Personal A Grades, 11 World Records and 7 Distinctions, Educate A Change.
Chapter 19 Answer Key
| Q | Ans | Q | Ans | Q | Ans | Q | Ans | Q | Ans |
|---|---|---|---|---|---|---|---|---|---|
| 1 | B | 11 | B | 21 | B | 31 | A | 41 | A |
| 2 | B | 12 | C | 22 | A | 32 | A | 42 | B |
| 3 | B | 13 | B | 23 | B | 33 | A | 43 | B |
| 4 | D | 14 | B | 24 | A | 34 | A | 44 | B |
| 5 | C | 15 | C | 25 | A | 35 | B | 45 | C |
| 6 | C | 16 | B | 26 | B | 36 | A | 46 | A |
| 7 | C | 17 | A | 27 | A | 37 | D | 47 | A |
| 8 | C | 18 | A | 28 | A | 38 | A | 48 | A |
| 9 | B | 19 | B | 29 | C | 39 | A | 49 | A |
| 10 | B | 20 | A | 30 | B | 40 | B | 50 | A |
For Full Scale Course: Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total Personal A Grades, 11 World Records and 7 Distinctions, Educate A Change.
Detailed Explanations
1. B
-
A freely suspended magnet aligns itself with Earth’s magnetic field.
-
Its north-seeking pole points approximately towards geographic north.
-
This is why a compass can be used for direction.
2. B
-
The north end of a compass needle points in the direction of the magnetic field.
-
Outside a bar magnet, magnetic field lines go from north to south.
-
Near the north pole of a magnet, the compass north end points away from that north pole.
3. B
-
Unlike magnetic poles attract.
-
North and south poles brought near each other attract.
4. D
-
Repulsion only occurs between like magnetic poles.
-
The two poles could both be north or both be south.
-
The only definite conclusion is that the poles are like.
5. C
-
A magnet can attract:
-
the opposite pole of another magnet
-
an unmagnetised magnetic material such as iron or steel
-
-
Attraction alone does not prove the object is a magnet.
6. C
-
Repulsion proves magnetism.
-
If the rod repels one pole of a known magnet, the rod must already have a like pole.
-
Attraction is not enough because ordinary iron can also be attracted.
7. C
-
Attraction can happen between:
-
unlike poles of magnets
-
a magnet and an unmagnetised magnetic material
-
-
Repulsion only happens between like magnetic poles.
-
That is why repulsion is the only sure test for a magnet.
8. C
-
A magnet always has both a north pole and a south pole.
-
If it is broken, each piece becomes a smaller magnet with its own north and south poles.
-
Single isolated poles are not produced.
9. B
-
Steel is suitable for permanent magnets because it is hard to magnetise but also hard to demagnetise.
-
Once magnetised, it keeps its magnetism well.
10. B
-
Soft iron is suitable for electromagnet cores because it is easily magnetised and easily demagnetised.
-
This allows the electromagnet to switch on and off effectively.
11. B
-
Stroking a steel needle repeatedly in the same direction with one pole of a magnet aligns its magnetic domains.
-
This magnetises the needle.
12. C
-
Heating strongly and cooling away from a magnetic field can demagnetise a magnet.
-
Heating disturbs the alignment of magnetic domains.
-
Letting it cool away from a field prevents the domains from realigning.
13. B
-
Hammering a magnet can disturb the alignment of its domains.
-
This may demagnetise it or weaken its magnetism.
14. B
-
Alternating current repeatedly reverses the magnetic field.
-
If the current is gradually reduced to zero, the magnetic domains become randomly arranged.
-
This demagnetises the magnet.
15. C
-
Magnetic field lines outside a bar magnet go from north to south.
-
Inside the magnet, the direction is from south to north.
-
Field lines form closed loops and never cross.
16. B
-
The magnetic field is strongest near the poles.
-
This is where the field lines are closest together.
17. A
-
Close field lines mean a stronger magnetic field.
-
Wider spacing means a weaker magnetic field.
18. A
-
A plotting compass shows the direction of the magnetic field at that point.
-
The north end of the compass points along the field direction.
19. B
-
Magnetic field direction is defined as the direction of the force on a north pole.
-
Outside a magnet, this is from north to south.
20. A
-
At a neutral point, magnetic fields from different sources cancel.
-
Resultant magnetic field strength is zero.
-
A compass placed there has no clear magnetic direction due to those magnets.
For Full Scale Course: Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total Personal A Grades, 11 World Records and 7 Distinctions, Educate A Change.
21. B
-
Two identical north poles facing each other produce opposite field directions at the midpoint.
-
The fields cancel at the centre.
-
This creates a neutral point.
22. A
-
Field lines go from north to south.
-
When unlike poles face each other, the fields in the gap reinforce.
-
The magnetic field in the gap becomes stronger.
23. B
-
Field lines leave a north pole and enter a south pole.
-
If lines leave X and enter Y:
-
X is north
-
Y is south
-
24. A
-
Iron filings become temporarily magnetised by induction.
-
Each filing behaves like a tiny magnet.
-
They align with the magnetic field, showing the field pattern.
25. A
-
Too close to a strong magnet, the compass needle is strongly affected and may not show the wider field pattern clearly.
-
For field plotting, compass readings should be taken at sensible distances and many points.
26. B
-
A north pole near soft iron induces the opposite pole at the nearest end.
-
So the end nearest the north pole becomes a south pole.
-
This causes attraction.
27. A
-
Soft iron is attracted to either pole because magnetic induction occurs.
-
The end nearest the magnet becomes the opposite pole.
-
Opposite poles attract.
28. A
-
The first nail becomes magnetised by induction.
-
It then behaves like a temporary magnet and attracts another nail.
-
This is temporary magnetism, not necessarily permanent magnetism.
29. C
-
Iron is easily magnetised.
-
It also loses magnetism easily when the magnetising field is removed.
-
That is why most nails fall off after the magnet is removed.
30. B
-
Steel is harder to magnetise than soft iron.
-
But once magnetised, it retains much of its magnetism.
-
This makes steel suitable for permanent magnets.
31. A
-
Soft iron:
-
easily magnetised
-
easily demagnetised
-
loses magnetism when current is switched off
-
-
Steel:
-
retains magnetism more strongly
-
-
So soft iron loses magnetism easily, while steel retains more.
32. A
-
A soft iron keeper helps preserve the magnet’s strength.
-
It provides an easy path for magnetic field lines.
-
This reduces loss of magnetism during storage.
33. A
-
A keeper completes a magnetic path between the poles.
-
This helps maintain the alignment of magnetic domains.
-
So it helps preserve magnetisation.
34. A
-
Magnets are best stored with unlike poles connected by soft iron keepers.
-
This completes the magnetic circuit and reduces demagnetisation.
-
Heating or leaving poles far apart is bad storage practice.
35. B
-
Iron and steel are magnetic materials.
-
Copper and aluminium are not strongly attracted by magnets.
-
So the attracted pieces are iron and steel.
36. A
-
Iron, steel and nickel are magnetic materials.
-
Copper, aluminium, brass, plastic and glass are not strongly magnetic.
37. D
-
Copper is not attracted strongly by a magnet.
-
Iron, nickel and steel are magnetic materials.
38. A
-
Not all metals are magnetic.
-
Only some metals such as iron, steel, nickel and cobalt are strongly magnetic.
-
Copper and aluminium are metals but are not strongly magnetic.
39. A
-
A current-carrying wire produces a magnetic field.
-
The compass deflects because its needle experiences a magnetic force.
40. B
-
The magnetic field around a straight current-carrying wire forms circles centred on the wire.
-
The direction depends on the direction of current.
For Full Scale Course: Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total Personal A Grades, 11 World Records and 7 Distinctions, Educate A Change.
41. A
-
Reversing the current reverses the direction of the magnetic field.
-
The shape of the field remains circular around the wire.
42. B
-
Increasing current increases the magnetic field strength around the wire.
-
A larger current produces a stronger magnetic effect.
43. B
-
The magnetic field around a current-carrying wire becomes weaker farther from the wire.
-
So the compass deflection becomes smaller.
44. B
-
Inside a long solenoid, the magnetic field is strong and nearly uniform.
-
The field pattern is similar to that inside a bar magnet.
45. C
-
A solenoid’s magnetic field is increased by:
-
increasing current
-
increasing number of turns
-
inserting a soft iron core
-
-
Copper is not suitable as a magnetic core.
46. A
-
The soft iron core becomes magnetised by the solenoid’s magnetic field.
-
Its magnetic field adds to the solenoid’s field.
-
This makes the electromagnet stronger.
47. A
-
Reversing the current reverses the magnetic field direction.
-
Therefore the north and south poles of the electromagnet reverse.
48. A
-
A scrapyard crane needs to pick up and then release iron/steel objects.
-
An electromagnet is useful because it can be switched on and off.
-
A permanent magnet would be annoying here. It would be clingy in the worst possible way.
49. A
-
When current flows in the relay coil, the coil becomes an electromagnet.
-
It attracts an iron armature.
-
This can close or open another circuit.
50. A
-
In an electric bell, the circuit repeatedly makes and breaks.
-
When current flows, the electromagnet attracts the armature and hammer.
-
This breaks the circuit, switching the electromagnet off.
-
The armature springs back, completing the circuit again.
-
This repeats rapidly, making the hammer vibrate.
For Full Scale Course: Written and Compiled By Sir Hunain Zia (AYLOTI), World Record Holder With 154 Total Personal A Grades, 11 World Records and 7 Distinctions, Educate A Change.
Common Traps From This Chapter
| Trap | Correct Rule |
|---|---|
| Freely suspended magnet | north-seeking pole points geographic north |
| Compass direction | north end points along magnetic field |
| Outside bar magnet | field lines go north to south |
| Like poles | repel |
| Unlike poles | attract |
| Attraction test | not proof of magnetism |
| Repulsion test | sure proof of magnetism |
| Breaking a magnet | each piece has north and south pole |
| Permanent magnet material | steel |
| Electromagnet core | soft iron |
| Soft iron | easily magnetised and demagnetised |
| Steel | retains magnetism |
| Demagnetising methods | heating, hammering, alternating current reduced to zero |
| Field line spacing | closer lines mean stronger field |
| Neutral point | resultant magnetic field is zero |
| Iron near magnet | opposite pole induced at nearest end |
| Magnetic materials | iron, steel, nickel, cobalt |
| Not all metals magnetic | copper and aluminium are not strongly attracted |
| Current in wire | produces circular magnetic field |
| Reverse current | reverse magnetic field direction |
| Increase current | stronger magnetic field |
| Solenoid field | strong and nearly uniform inside |
| Stronger electromagnet | more turns, larger current, soft iron core |
| Reverse electromagnet poles | reverse current |
| Relay | electromagnet attracts armature |
| Electric bell | make-break circuit repeatedly switches electromagnet on/off |