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1. A compass needle turns and settles along a particular direction even when no object is touching it. This observation mainly shows that magnetism can produce
ⓐ. a non-contact effect
ⓑ. only a heating effect
ⓒ. a contact force only
ⓓ. only a change in mass
Correct Answer: a non-contact effect
Explanation: Magnetism can act without direct physical contact between the magnet and the affected object. A compass needle turns because it experiences a magnetic effect due to Earth's magnetic field. The needle does not need to touch Earth or another magnet for this turning to occur. This is why magnetic force is described as a non-contact effect. Contact forces such as friction need touching surfaces, while a magnetic effect can be observed through space around a magnet.
2. In a simple bar magnet, the end that tends to point approximately toward geographic north when freely suspended is called the
ⓐ. south-seeking pole
ⓑ. electric pole
ⓒ. north-seeking pole
ⓓ. neutral pole
Correct Answer: north-seeking pole
Explanation: A freely suspended bar magnet settles approximately along the north-south direction. The end that points toward geographic north is called the north-seeking pole or \(N\)-pole. The opposite end is called the south-seeking pole or \(S\)-pole. These names describe the direction-seeking behaviour of the magnet, not the idea that the magnet has only one pole. Both \(N\) and \(S\) poles occur together in an ordinary magnet.
3. Two bar magnets are brought close to each other. Their \(N\)-poles are facing each other. What should be observed?
ⓐ. They become electrically charged
ⓑ. They repel each other
ⓒ. They attract strongly
ⓓ. They lose both poles permanently
Correct Answer: They repel each other
Explanation: Like magnetic poles repel each other, so two \(N\)-poles facing each other produce repulsion. Similarly, two \(S\)-poles also repel each other. Unlike poles, such as \(N\) and \(S\), attract each other. This rule is a basic way to identify magnetic pole behaviour. The repulsion here is magnetic in nature and does not require the magnets to become electrically charged.
4. A naturally occurring magnetic mineral that can attract small pieces of iron is best described as
ⓐ. a natural magnet
ⓑ. a demagnetised material
ⓒ. a non-magnetic insulator
ⓓ. an artificial magnet
Correct Answer: a natural magnet
Explanation: A natural magnet is a material found in nature that shows magnetic properties. Lodestone is a common example of a naturally occurring magnetic mineral. An artificial magnet is made by magnetising a suitable material such as steel or iron. A demagnetised material has lost most of its magnetic alignment and does not behave like a strong magnet. The key distinction is whether the magnetic behaviour is naturally present or produced by human action.
5. A bar magnet has its ends marked \(N\) and \(S\). The symbols \(N\) and \(S\) refer to
ⓐ. two different SI units
ⓑ. positive and negative electric charges
ⓒ. two values of magnetic field strength
ⓓ. two kinds of magnetic poles
Correct Answer: two kinds of magnetic poles
Explanation: The symbols \(N\) and \(S\) stand for north-seeking and south-seeking magnetic poles. They are not electric charge signs like \(+\) and \(-\). A magnet has two poles, and its interactions depend on whether like or unlike poles face each other. Magnetic poles are used to describe attraction, repulsion, and field direction around magnets. Confusing \(N\) and \(S\) with electric charge signs leads to wrong comparisons between magnetism and electrostatics.
6. A small iron pin is placed near one end of a bar magnet and gets attracted. This attraction is an example of
ⓐ. optical reflection
ⓑ. magnetic interaction
ⓒ. gravitational shielding
ⓓ. thermal conduction
Correct Answer: magnetic interaction
Explanation: A bar magnet can attract magnetic materials such as iron. The iron pin is affected because it lies in the region where the magnet has influence. This region is described using the magnetic field concept later, but the basic observation is magnetic attraction. Thermal conduction and optical reflection involve heat and light, not attraction of iron by a magnet. The example shows how magnetism is recognised through forces on suitable materials.
7. A magnetic field around a magnet is best understood as the region where
ⓐ. only electric current can exist
ⓑ. gravity becomes zero
ⓒ. temperature must increase
ⓓ. magnetic influence is detectable
Correct Answer: magnetic influence is detectable
Explanation: The magnetic field is the region around a magnet where its magnetic effect can be experienced. A compass needle or a small magnetic object can be used to detect this influence. The field is not limited to the visible body of the magnet; it extends into the surrounding space. Magnetic field does not mean that gravity disappears or that temperature must change. This field idea helps describe magnetic effects without requiring direct contact.
8. The vector symbol commonly used for magnetic field is
ⓐ. \(R\)
ⓑ. \(I\)
ⓒ. \(\vec{E}\)
ⓓ. \(\vec{B}\)
Correct Answer: \(\vec{B}\)
Explanation: Magnetic field is commonly represented by the vector symbol \(\vec{B}\). The arrow on \(\vec{B}\) reminds us that magnetic field has both magnitude and direction. The symbol \(\vec{E}\) is used for electric field, not magnetic field. Symbols such as \(I\) and \(R\) usually represent current and resistance in circuit contexts. Using \(\vec{B}\) consistently is important because later formulas depend on the direction of the magnetic field.
9. The SI unit of magnetic field \(B\) is
ⓐ. \(coulomb\)
ⓑ. \(tesla\)
ⓒ. \(newton\)
ⓓ. \(ohm\)
Correct Answer: \(tesla\)
Explanation: The SI unit of magnetic field \(B\) is \(tesla\), written as \(T\). This unit measures the strength of a magnetic field. A larger value in \(T\) means a stronger magnetic field, if the comparison is made at similar points or conditions. Units such as \(newton\), \(coulomb\), and \(ohm\) belong to force, charge, and resistance respectively. The symbol \(T\) should not be confused with temperature unless the context clearly indicates temperature.
10. A magnetic field value is written as \(0.20\,T\). Using \(1\,T=10^4\,G\), what is the same field in \(G\)?
ⓐ. \(2000\,G\)
ⓑ. \(500\,G\)
ⓒ. \(200\,G\)
ⓓ. \(1000\,G\)
Correct Answer: \(2000\,G\)
Explanation: \( \textbf{Given relation:} \) \(1\,T=10^4\,G\).
\( \textbf{Given field:} \) \(B=0.20\,T\).
\( \textbf{Required:} \) Field value in \(G\).
Since \(1\,T\) corresponds to \(10^4\,G\), multiply the value in \(T\) by \(10^4\).
\[
B=0.20\times10^4\,G
\]
\[
0.20\times10^4=2.0\times10^3
\]
\[
B=2000\,G
\]
\( \textbf{Final answer:} \) The magnetic field is \(2000\,G\).
The multiplication by \(10^4\) is needed when converting from \(T\) to \(G\), while division by \(10^4\) would be used for the reverse conversion.
11. Study the entries below and choose the row in which both symbol and meaning are matched properly.
| Row | Symbol | Meaning |
|---|---|---|
| P | \(N\) | South-seeking pole |
| Q | \(S\) | North-seeking pole |
| R | \(\vec{B}\) | Magnetic field |
| S | \(T\) | Electric charge |
ⓐ. Row R
ⓑ. Row S
ⓒ. Row Q
ⓓ. Row P
Correct Answer: Row R
Explanation: The symbol \(\vec{B}\) represents magnetic field. The vector arrow shows that magnetic field has a direction as well as a magnitude. Row P is wrong because \(N\) denotes the north-seeking pole, not the south-seeking pole. Row Q is wrong because \(S\) denotes the south-seeking pole, not the north-seeking pole. Row S is wrong because \(T\) stands for \(tesla\), the SI unit of magnetic field, not electric charge. The safest way to read these symbols is to connect \(N\) and \(S\) with poles, \(\vec{B}\) with field, and \(T\) with unit.
12. A compass needle placed at a point near a magnet turns so that it has one definite direction. This behaviour shows that magnetic field at a point is treated as
ⓐ. a scalar quantity with no direction
ⓑ. a quantity that exists only inside the magnet
ⓒ. a vector quantity with direction
ⓓ. a unitless number
Correct Answer: a vector quantity with direction
Explanation: A magnetic field at a point has a definite direction, as shown by the direction in which a compass needle aligns. A quantity with both magnitude and direction is treated as a vector quantity. The magnetic field is therefore represented as \(\vec{B}\), not just as a number without direction. It can exist outside the magnet as well as inside magnetic materials. The compass does not merely show that a field is present; it also gives information about the direction of \(\vec{B}\) at that point.
13. A magnetic field line is drawn through a point near a bar magnet. The direction of \(\vec{B}\) at that point is given by
ⓐ. the longest nearby field line
ⓑ. the tangent to the field line
ⓒ. the direction opposite to all field lines
ⓓ. the normal to the field line
Correct Answer: the tangent to the field line
Explanation: A magnetic field line is a visual way of representing the direction of magnetic field in space. At any point on a field line, the tangent drawn to the line gives the direction of \(\vec{B}\) at that point. The normal to the line would point sideways and would not represent the field direction. The length of a field line is also not used to decide the local direction of \(\vec{B}\). This tangent rule becomes important later when field patterns near a bar magnet are interpreted without using a physical compass.
14. A field value is recorded as \(7500\,G\). Using \(1\,T=10^4\,G\), the value in \(T\) is
ⓐ. \(75\,T\)
ⓑ. \(0.075\,T\)
ⓒ. \(7.5\,T\)
ⓓ. \(0.75\,T\)
Correct Answer: \(0.75\,T\)
Explanation: \( \textbf{Given relation:} \) \(1\,T=10^4\,G\).
\( \textbf{Given field:} \) \(B=7500\,G\).
\( \textbf{Required:} \) Field in \(T\).
To convert from \(G\) to \(T\), divide the value in \(G\) by \(10^4\).
\[
B=\frac{7500}{10^4}\,T
\]
\[
B=0.7500\,T
\]
\[
B=0.75\,T
\]
\( \textbf{Final answer:} \) The magnetic field is \(0.75\,T\).
Multiplication by \(10^4\) would convert \(T\) into \(G\), so using it here would reverse the conversion direction.
15. In a short note, the magnetic field is written only as \(B=3.0\,T\), while the compass direction at that point is also known. A more complete physical description should include
ⓐ. magnitude and direction of \(\vec{B}\)
ⓑ. only the mass of the compass needle
ⓒ. only the colour of the magnet
ⓓ. the electric charge of the magnet
Correct Answer: magnitude and direction of \(\vec{B}\)
Explanation: Magnetic field is a vector quantity, so a complete description needs both magnitude and direction. The value \(3.0\,T\) gives only the magnitude of the field. The compass direction gives the missing directional information. The colour of the magnet and the mass of the compass needle do not specify the magnetic field at the point. Writing \(\vec{B}\) instead of just \(B\) reminds us that direction is part of the quantity.
16. A bar magnet is freely suspended and then rotated slightly away from its settled position. It turns back toward its original north-south alignment mainly because
ⓐ. the magnet loses its poles during rotation
ⓑ. the magnetic field becomes a scalar quantity
ⓒ. magnetic effects can produce a turning action
ⓓ. the \(N\)-pole becomes an \(S\)-pole temporarily
Correct Answer: magnetic effects can produce a turning action
Explanation: A freely suspended magnet tends to settle along the direction of the surrounding magnetic field. When it is disturbed, magnetic interaction can produce a turning effect that brings it back toward its preferred alignment. The poles of the magnet do not disappear during ordinary rotation. The \(N\)-pole and \(S\)-pole also do not exchange identities just because the magnet is turned. This observation is an early sign that magnetism involves direction, not merely attraction and repulsion.
17. Match the magnetic terms with their basic meanings.
| Column I | Column II |
|---|---|
| P. \(T\) | 1. Unit smaller than tesla |
| Q. \(G\) | 2. SI unit of magnetic field |
| R. \(\vec{B}\) | 3. North-seeking pole |
| S. \(N\) | 4. Magnetic field vector |
ⓐ. P-1, Q-2, R-4, S-3
ⓑ. P-2, Q-1, R-3, S-4
ⓒ. P-4, Q-1, R-2, S-3
ⓓ. P-2, Q-1, R-4, S-3
Correct Answer: P-2, Q-1, R-4, S-3
Explanation: The symbol \(T\) represents \(tesla\), the SI unit of magnetic field. The symbol \(G\) represents \(gauss\), a smaller unit used for magnetic field. The vector symbol \(\vec{B}\) represents magnetic field with direction included. The symbol \(N\) marks the north-seeking pole of a magnet. The main separation is between pole symbols such as \(N\) and \(S\), and field or unit symbols such as \(\vec{B}\), \(T\), and \(G\).
18. Two small magnetic needles are placed at different points near a bar magnet. Needle P turns more strongly and settles quickly, while needle Q turns weakly. The better inference is that
ⓐ. magnetic field exists only at Q
ⓑ. magnetic field has no direction at P
ⓒ. magnetic field is stronger at P than at Q
ⓓ. needle P has changed into an electric charge
Correct Answer: magnetic field is stronger at P than at Q
Explanation: The turning of a magnetic needle shows that it experiences a magnetic influence. A stronger turning effect generally indicates a stronger magnetic field at that position, assuming similar needles are used. A weak turning effect does not mean there is no field; it may mean the field is weaker. The direction of settling still shows that \(\vec{B}\) has a direction. The observation should be read as a difference in magnetic field strength, not as a change of the needle into electric charge.
19. A bar magnet is cut into two equal pieces perpendicular to its length. Each piece will behave as
ⓐ. only an isolated \(N\)-pole
ⓑ. a non-magnetic object with no poles
ⓒ. a smaller magnet with \(N\) and \(S\) poles
ⓓ. only an isolated \(S\)-pole
Correct Answer: a smaller magnet with \(N\) and \(S\) poles
Explanation: Magnetic poles are not obtained as isolated single poles by cutting an ordinary bar magnet. When a bar magnet is cut, each piece behaves as a smaller magnet with its own \(N\)-pole and \(S\)-pole. This is very different from separating positive and negative electric charges in some electrostatic situations. The cut creates new pole faces, but it does not produce a single isolated magnetic pole. This pole-pair behaviour is why a bar magnet is naturally treated as a magnetic dipole.
20. The pole-pair nature of a bar magnet means that the magnet is best described as
ⓐ. a single north pole
ⓑ. a magnetic dipole
ⓒ. a magnetic monopole
ⓓ. an electric dipole only
Correct Answer: a magnetic dipole
Explanation: A bar magnet has two magnetic poles, \(N\) and \(S\), separated by a finite distance. Such a pair is called a magnetic dipole. A magnetic monopole would mean an isolated single magnetic pole, but this is not observed in ordinary magnetism. The word dipole here does not mean an electric dipole; it refers to the magnetic pole pair of a magnet. The two-pole structure is central to later ideas such as magnetic dipole moment and dipole field.