Maharashtra Board Class 11 Physics Chapter 12 Magnetism Solutions

1. Choose The Correct Option.

Question 1. Let r be the distance of a point on the axis of a bar magnet from its center. The magnetic field at r is always proportional to
(A) \(\frac{1}{r^{2}}\)
(B) \(\frac{1}{r^{3}}\)
(C) \(\frac{1}{r}\)
(D) Not necessarily \(\frac{1}{r^{3}}\) at all points
Answer: (B) \(\frac{1}{r^{3}}\)
In simple words: The magnetic field strength along the axial line of a short bar magnet is inversely proportional to the cube of the distance from its center. This relationship is a fundamental characteristic of dipole fields.

🎯 Exam Tip: Remember the inverse cube relationship for the magnetic field on the axis of a bar magnet, which is a common formula tested in magnetism problems.

Question 2. Magnetic meridian is the plane
(A) perpendicular to the magnetic axis of Earth
(B) perpendicular to geographic axis of Earth
(C) passing through the magnetic axis of Earth
(D) passing through the geographic axis
Answer: (C) passing through the magnetic axis of Earth
In simple words: The magnetic meridian at a place is an imaginary vertical plane that passes through the magnetic axis of the Earth at that location, indicating the direction a freely suspended magnet would align.

🎯 Exam Tip: Distinguish between magnetic meridian (related to Earth's magnetic field) and geographic meridian (related to Earth's rotational axis) for accurate answers.

Question 3. The horizontal and vertical component of magnetic field of Earth are same at some place on the surface of Earth. The magnetic dip angle at this place will be
(A) 30°
(B) 45°
(C) 0°
(D) 90°
Answer: (B) 45°
In simple words: The angle of dip is the angle between the Earth's total magnetic field and the horizontal direction. If the horizontal and vertical components are equal, then \(\tan(\text{dip angle}) = \frac{\text{Vertical component}}{\text{Horizontal component}} = 1\), which means the dip angle is 45°.

🎯 Exam Tip: Know the definition of the angle of dip and its relation to horizontal and vertical magnetic field components, particularly that it's 45° when components are equal.

Question 4. Inside a bar magnet, the magnetic field lines
(A) are not present
(B) are parallel to the cross sectional area of the magnet
(C) are in the direction from N pole to S pole
(D) are in the direction from S pole to N pole
Answer: (D) are in the direction from S pole to N pole
In simple words: Outside a bar magnet, magnetic field lines run from the North pole to the South pole. However, inside the magnet, to form continuous closed loops, they run from the South pole to the North pole.

🎯 Exam Tip: Always remember that magnetic field lines form closed loops, extending from N to S outside the magnet and S to N inside the magnet.

Question 5. A place where the vertical components of Earth's magnetic field is zero has the angle of dip equal to
(A) 0°
(B) 45°
(C) 60°
(D) 90°
Answer: (A) 0°
In simple words: The angle of dip is the angle between the horizontal and the resultant magnetic field. If the vertical component is zero, the magnetic field is entirely horizontal, making the dip angle 0°. This occurs at the magnetic equator.

🎯 Exam Tip: Understand that a zero vertical component corresponds to the magnetic equator, where the dip angle is 0°, and a zero horizontal component corresponds to the magnetic poles, where the dip angle is 90°.

Question 6. A place where the horizontal component of Earth's magnetic field is zero lies at
(A) geographic equator
(B) geomagnetic equator
(C) one of the geographic poles
(D) one of the geomagnetic poles
Answer: (D) one of the geomagnetic poles
In simple words: At the geomagnetic poles, the Earth's magnetic field lines are vertical, meaning there is no horizontal component. This results in an angle of dip of 90° at these locations.

🎯 Exam Tip: Remember that the horizontal component of Earth's magnetic field is zero at the magnetic poles, leading to a dip angle of 90°.

Question 7. A magnetic needle kept nonparallel to the magnetic field in a nonuniform magnetic field experiences
(A) a force but not a torque
(B) a torque but not a force
(C) both a force and a torque
(D) neither force nor a torque
Answer: (C) both a force and a torque
In simple words: In a non-uniform magnetic field, a magnetic dipole (like a needle) experiences a net force because the field strength varies across its poles, and it also experiences a torque if it's not aligned with the field direction.

🎯 Exam Tip: For a magnetic dipole in a non-uniform field, both a net force (due to field gradient) and a torque (due to misalignment) are generally experienced, unlike a uniform field where only torque is present.

2. Answer The Following Questions In Brief.

Question 1. What happens if a bar magnet is cut into two pieces transverse to its length/along its length?
Answer:
i. When a magnet is cut into two pieces, then each piece behaves like an independent magnet.
ii. When a bar magnet is cut transverse to its length, the two pieces generated will behave as independent magnets of reduced magnetic length. However, the pole strength of all the four poles formed will be same as that of the original bar magnet. Thus, the new dipole moment of the smaller magnets will be,
\(\vec{m}_{1} = qm \left( l_1 \right)\), \(\vec{m}_{2} = qm \left( l_2 \right)\)

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र दर्शाता है कि एक बार चुंबक को उसकी लंबाई के अनुप्रस्थ (बीच से) काटने पर क्या होता है। मूल चुंबक दो छोटे चुंबकों में विभाजित हो जाता है, जिनमें से प्रत्येक का अपना उत्तरी और दक्षिणी ध्रुव होता है। नए चुंबकों की चुंबकीय लंबाई कम हो जाती है, लेकिन ध्रुवीय शक्ति वही रहती है।
iii. When the bar magnet is cut along its length, the two pieces generated will behave like an independent magnet with reduced pole strength. However, the magnetic length of both the new magnets will be same as that of the original bar magnet. Thus, the new dipole moment of the smaller magnets will be,
\(\vec{m}_{1} = (qm)_{1} (2l)\), \(\vec{m}_{2} = (qm)_{2} (2l)\)

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र दर्शाता है कि एक बार चुंबक को उसकी लंबाई के अनुदैर्ध्य (लंबाई के साथ) काटने पर क्या होता है। मूल चुंबक दो पतले चुंबकों में विभाजित हो जाता है। इस मामले में, चुंबकीय लंबाई समान रहती है, लेकिन प्रत्येक नए चुंबक की ध्रुवीय शक्ति कम हो जाती है।
In simple words: When a bar magnet is cut, whether transversely or longitudinally, each piece becomes a new, complete magnet with its own North and South poles. Transverse cuts reduce magnetic length but keep pole strength, while longitudinal cuts reduce pole strength but keep magnetic length.

🎯 Exam Tip: Understand the concept that magnetic monopoles do not exist; cutting a magnet always results in smaller magnets, each with both poles. Differentiate the effect on magnetic length and pole strength for transverse vs. longitudinal cuts.

Question 2. What could be the equation for Gauss' law of magnetism, if a monopole of pole strength p is enclosed by a surface?
Answer:
i. According to Gauss' law of electrostatics, the net electric flux through any Gaussian surface is proportional to net charge enclosed in it. The equation is given
as, \(\emptyset_{E} = \oint \vec{E} \cdot d\vec{S} = \frac{q}{\varepsilon_{0}}\)
ii. Similarly, if a monopole of a magnet of pole strength p exists, the Gauss' law of magnetism in S.I. units will be given as, \(\emptyset_{E} = \oint \vec{B} \cdot d\vec{S} = \mu_{0}P\)
In simple words: If magnetic monopoles existed, Gauss's law for magnetism would resemble Gauss's law for electrostatics, with the magnetic flux through a closed surface being proportional to the enclosed magnetic pole strength \(P\) and the magnetic permeability \(\mu_0\).

🎯 Exam Tip: Recognize the fundamental difference between electrostatics and magnetism: the non-existence of magnetic monopoles. Gauss's law for magnetism reflects this by stating the net magnetic flux through any closed surface is zero in reality.

3. Answer The Following Questions In Detail.

Question 1. Explain the Gauss' law for magnetic fields.
Answer:
i. Analogous to the Gauss' law for electric field, the Gauss' law for magnetism states that, the net magnetic flux (\(\emptyset_{B}\)) through a closed Gaussian surface is zero. \(\emptyset_{B} = \oint \vec{B} \cdot d\vec{S} = 0\)
ii. Consider a bar magnet, a current carrying solenoid and an electric dipole. The magnetic field lines of these three are as shown in figures.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र तीन अलग-अलग स्रोतों- एक बार चुंबक, एक धारा-वाहक परिनालिका और एक विद्युत द्विध्रुव के चुंबकीय क्षेत्र रेखाओं को दर्शाता है। प्रत्येक के लिए, दो बंद गाऊसी सतहें (P और Q) दिखाई गई हैं। ये चित्र गाऊसी नियम को चुंबकीय क्षेत्रों के लिए समझने में मदद करते हैं, यह दर्शाते हुए कि चुंबकीय क्षेत्र रेखाएं बंद लूप बनाती हैं।
iii. The areas (P) and (Q) are the cross - sections of three dimensional closed Gaussian surfaces. The Gaussian surface (P) does not include poles while the Gaussian surface (Q) includes N-pole of bar magnet, solenoid and the positive charge in case of electric dipole.
iv. The number of lines of force entering the surface (P) is equal to the number of lines of force leaving the surface. This can be observed in all the three cases.
v. However, Gaussian surface (Q) of bar magnet, enclose north pole. As, even thin slice of a bar magnet will have both north and south poles associated with it, the number of lines of Force entering surface (Q) are equal to the number of lines of force leaving the surface.
vi. For an electric dipole, the field lines begin from positive charge and end on negative charge. For a closed surface (Q), there is a net outward flux since it does include a net (positive) charge.
vii. Thus, according to the Gauss' law of electrostatics \(\emptyset_{E} = \oint \vec{E} \cdot d\vec{S} = \frac{q}{\varepsilon_{0}}\), where q is the positive charge enclosed.
viii. The situation is entirely different from magnetic lines of force. Gauss' law of magnetism can be written as \(\emptyset_{B} = \oint \vec{B} \cdot d\vec{S} = 0\)
From this, one can conclude that for electrostatics, an isolated electric charge exists but an isolated magnetic pole does not exist.
In simple words: Gauss's law for magnetism states that the total magnetic flux through any closed surface is always zero. This implies that magnetic monopoles do not exist; magnetic field lines always form continuous closed loops, having no starting or ending points.

🎯 Exam Tip: Focus on the zero net magnetic flux for closed surfaces as the core concept of Gauss's law for magnetism, directly linking it to the absence of magnetic monopoles.

Question 2. What is a geographic meridian? How does the declination vary with latitude? Where is it minimum?
Answer:
A plane perpendicular to the surface of the Earth (vertical plane) and passing through geographic axis is geographic meridian.
i. Angle between the geographic and the magnetic meridian at a place is called magnetic declination (a).
ii. Magnetic declination varies with location and over time. As one moves away from the true north the declination changes depending on the latitude as well as longitude of the place. By convention, declination is positive when magnetic north is east of true north, and negative when it is to the west. The declination is small in India. It is 0° 58′ west at Mumbai and 0° 41' east at Delhi.
In simple words: A geographic meridian is a vertical plane passing through the Earth's geographic axis. Magnetic declination, the angle between geographic and magnetic meridians, changes with location and time, being small in India.

🎯 Exam Tip: Define geographic meridian clearly and explain magnetic declination as the angular difference between geographic and magnetic north, noting its variability and small values in India.

Question 3. Define the angle of dip. What happens to angle of dip as we move towards magnetic pole from magnetic equator?
Answer:
Angle made by the direction of resultant magnetic field with the horizontal at a place is inclination or angle of dip (\(\emptyset\)) at the place.
At the magnetic pole value of \(\emptyset = 90^\circ\) and it goes on decreasing when we move towards equator such that at equator value of (\(\emptyset\)) = \(0^\circ\).
In simple words: The angle of dip is the inclination of the Earth's total magnetic field with the horizontal. It is 90° at the magnetic poles and decreases to 0° at the magnetic equator.

🎯 Exam Tip: Clearly define the angle of dip and remember its extreme values: 90° at the magnetic poles and 0° at the magnetic equator, and how it varies between these points.

4. Solve The Following Problems.

Question 1. A magnetic pole of bar magnet with pole strength of 100 Am is 20 cm away from the centre of a bar magnet. Bar magnet has pole strength of 200 Am and has a length 5 cm. If the magnetic pole is on the axis of the bar magnet, find the force on the magnetic pole.
Answer:
Given that, \((q_m)_1 = 200 Am\)
and \((2l) = 5 cm = 5 \times 10^{-2} m\)
\(\therefore m = 200 \times 5 \times 10^{-2} = 10 Am^2\)
For a bar magnet, magnetic dipole moment is,
\(m = q_m (2l)\)
For a point on the axis of a bar magnet at distance, \(r = 20 cm = 0.2 m\),
\(B_a = \frac{\mu_0}{4\pi} \frac{2m}{r^3}\)
\( = 10^{-7} \times \frac{2 \times 10}{(0.2)^3}\)
\( = 0.25 \times 10^{-3}\)
\( = 2.5 \times 10^{-4} Wb/m^2\)
The force acting on the pole will be given by,
\(F = q_m B_a = 100 \times 2.5 \times 10^{-4}\)
\( = 2.5 \times 10^{-2} N\)
In simple words: This problem involves calculating the magnetic field produced by a bar magnet at a point on its axis and then determining the force experienced by another magnetic pole placed at that point using the dipole moment and the field formula.

🎯 Exam Tip: Ensure correct unit conversions (cm to m) and use the appropriate formula for magnetic field on the axial line of a bar magnet, then apply \(F = q_m B\) for force calculation.

Question 2. A magnet makes an angle of 45° with the horizontal in a plane making an angle of 30° with the magnetic meridian. Find the true value of the dip angle at the place.
Answer:
Let true value of dip be \(\emptyset\). When the magnet is kept 45° aligned with declination 30°, the horizontal component of Earth's magnetic field.
\(B'_H = B_H \cos 30^\circ\) Whereas, vertical component remains unchanged.
\(\therefore\) For apparent dip of \(45^\circ\),
\(\tan 45^\circ = \frac{B'_V}{B'_H} = \frac{B_V}{B_H \cos 30^\circ} = \frac{B_V}{B_H} \times \frac{1}{\cos 30^\circ}\)
But, real value of dip is,
\(\tan \emptyset = \frac{B_V}{B_H}\)
\(\therefore \tan 45^\circ = \frac{\tan \emptyset}{\cos 30^\circ}\)
\(\therefore \tan \emptyset = \tan 45^\circ \times \cos 30^\circ\)
\( = 1 \times \frac{\sqrt{3}}{2}\)
\(\therefore \emptyset = \tan^{-1} (0.866)\)
In simple words: This problem uses the relationship between true dip angle, apparent dip angle, and the angle of declination to find the actual dip. The vertical component of Earth's field remains constant, while the effective horizontal component changes based on the alignment angle.

🎯 Exam Tip: Remember the formula relating true dip (\(\emptyset\)), apparent dip (\(\emptyset'\)), and the angle of the plane with the magnetic meridian (\(\alpha\)): \(\tan \emptyset' = \frac{\tan \emptyset}{\cos \alpha}\). This is crucial for solving problems involving apparent dip.

Question 3. Two small and similar bar magnets have magnetic dipole moment of 1.0 Am² each. They are kept in a plane in such a way that their axes are perpendicular to each other. A line drawn through the axis of one magnet passes through the centre of other magnet. If the distance between their centres is 2 m, find the magnitude of magnetic field at the midpoint of the line joining their centres.
Answer:
Let P be the midpoint of the line joining the centres of two bar magnets. As shown in figure, P is at the axis of one bar magnet and at the equator of another bar magnet. Thus, the magnetic field on the axis of the first bar magnet at distance of 1 m from the centre will be,

ℹ️ चित्र व्याख्या (Diagram Explanation): इस चित्र में दो बार चुंबक दिखाए गए हैं जिनके अक्ष एक-दूसरे के लंबवत हैं और उनके केंद्र को जोड़ने वाली रेखा के मध्यबिंदु P को दर्शाया गया है। पहला चुंबक P पर अक्षीय क्षेत्र बनाता है, जबकि दूसरा चुंबक P पर भूमध्यरेखीय क्षेत्र बनाता है। परिणामी क्षेत्र इन दोनों का सदिश योग होता है।
\(B_a = \frac{\mu_0}{4\pi} \frac{2m}{r^3}\)
\( = 10^{-7} \times \frac{2 \times 1.0}{(1)^3}\)
\( = 2 \times 10^{-7} Wb/m^2\)
Magnetic field on the equator of second bar magnet will be,
\(B_{eq} = \frac{\mu_0}{4\pi} \frac{m}{r^3}\)
\( = 10^{-7} \times \frac{1.0}{(1)^3}\)
\( = 1 \times 10^{-7} Wb/m^2\)
The net magnetic field at P,
\(B_{net} = \sqrt{B_a^2 + B_{eq}^2}\)
\( = \sqrt{(2 \times 10^{-7})^2 + (1 \times 10^{-7})^2}\)
\( = \sqrt{(10^{-7})^2 \times (4+1)}\)
\( = \sqrt{5} \times 10^{-7} Wb/m^2\)
In simple words: This problem involves calculating the magnetic field at a midpoint P due to two perpendicular bar magnets. P is axial for one magnet and equatorial for the other. The total magnetic field is the vector sum of these two fields, calculated using their respective formulas.

🎯 Exam Tip: When dealing with multiple magnets, calculate the magnetic field due to each magnet independently at the desired point (axial or equatorial), then find the vector sum to get the net magnetic field. Pay attention to the directions of the fields.

Question 4. A circular magnet is made with its north pole at the centre, separated from the surrounding circular south pole by an air gap. Draw the magnetic field lines in the gap. Draw a diagram to illustrate the magnetic lines of force between the south poles of two such magnets.
Answer:
i. For a circular magnet:

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक वृत्ताकार चुंबक को दर्शाता है जिसका उत्तरी ध्रुव केंद्र में है और चारों ओर एक वृत्ताकार दक्षिणी ध्रुव है, जिसके बीच में एक वायु अंतराल है। चुंबकीय क्षेत्र रेखाएं केंद्र में उत्तरी ध्रुव से निकलकर बाहरी वृत्ताकार दक्षिणी ध्रुव में प्रवेश करती हुई दिखाई गई हैं।
ii. For south poles of such circular magnets facing each other:

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र दो वृत्ताकार चुंबकों के दक्षिणी ध्रुवों के बीच चुंबकीय क्षेत्र रेखाओं को दर्शाता है जब वे एक-दूसरे के सामने होते हैं। प्रतिकर्षण के कारण क्षेत्र रेखाएं एक-दूसरे से दूर मुड़ जाती हैं, जिससे यह संकेत मिलता है कि समान ध्रुव एक-दूसरे को प्रतिकर्षित करते हैं।
For south poles of bar magnets facing each other:

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र दो बार चुंबकों के दक्षिणी ध्रुवों के बीच चुंबकीय क्षेत्र रेखाओं को दर्शाता है जब वे एक-दूसरे के सामने होते हैं। क्षेत्र रेखाएं ध्रुवों के बीच से दूर मुड़ती हैं, जो समान ध्रुवों के बीच प्रतिकर्षण बल को प्रदर्शित करती हैं।
In simple words: Magnetic field lines for a circular magnet with a central N-pole and outer S-pole go from the center outwards. When two south poles face each other, the field lines repel, curving away from the region between the poles, showing the repulsion between like poles.

🎯 Exam Tip: Practice drawing magnetic field lines for various configurations, remembering that lines originate from N-poles and end at S-poles, never cross, and are denser where the field is stronger. Pay special attention to repulsion between like poles.

Question 5. Two bar magnets are placed on a horizontal surface. Draw magnetic lines around them. Mark the position of any neutral points (points where there is no resultant magnetic field) on your diagram.
Answer:
The magnetic lines of force between two magnets will depend on their relative positions. Considering the magnets to be placed one besides the other as shown
in figure, the magnetic lines of force will be as shown.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र दो बार चुंबकों को दर्शाता है जो एक क्षैतिज सतह पर एक-दूसरे के बगल में रखे गए हैं। चुंबकीय क्षेत्र रेखाएं उत्तरी ध्रुव से निकलकर दक्षिणी ध्रुव में प्रवेश करती हैं। तटस्थ बिंदु (जहाँ परिणामी चुंबकीय क्षेत्र शून्य होता है) उन क्षेत्रों में स्थित होते हैं जहाँ विपरीत ध्रुवों के क्षेत्र एक-दूसरे को निरस्त करते हैं, जैसा कि मध्य में N-N और S-S के बीच दिखाया गया है।
In simple words: When two bar magnets are placed side-by-side, magnetic field lines emerge from North poles and enter South poles. Neutral points, where the net magnetic field is zero, occur at locations where the field lines from both magnets cancel each other out, often between like poles.

🎯 Exam Tip: When drawing magnetic field lines for two magnets, correctly depict attraction/repulsion patterns and precisely locate neutral points where the magnetic field from both magnets effectively cancels out, indicating zero resultant field.

Can You Recall? (Textbook Page No. 221)

Question 1. What are the magnetic lines of force?
Answer:
The magnetic field around a magnet is shown by lines going from one end of the magnet to the other. These lines are named as magnetic lines of force.
In simple words: Magnetic lines of force are imaginary lines used to represent the direction and strength of a magnetic field around a magnet. They indicate the path a hypothetical isolated North pole would follow.

🎯 Exam Tip: Define magnetic lines of force as a visual representation of the magnetic field, indicating its direction and strength.

Question 2. What are the rules concerning the lines of force?
Answer:
i. Magnetic lines of force originate from the north pole and end at the south pole.
ii. The magnetic lines of force of a magnet or a solenoid form closed loops. This is in contrast to the case of an electric dipole, where the electric lines of force originate from the positive charge and end on the negative charge.
iii. The direction of the net magnetic field \(\vec{B}\) at a point is given by the tangent to the magnetic line of force at that point.
iv. The number of lines of force crossing per unit area decides the magnitude of magnetic field \(\vec{B}\)
v. The magnetic lines of force do not intersect. This is because had they intersected, the direction of magnetic field would not be unique at that point.
In simple words: Magnetic field lines originate from North poles, end at South poles, form closed loops, never intersect, and their tangent gives the field direction. Their density indicates field strength.

🎯 Exam Tip: List the key properties of magnetic field lines accurately, especially the closed-loop nature and the non-intersection rule, which are fundamental to magnetism.

Question 3. What is a bar magnet?
Answer:
Bar magnet is a magnet in the shape of bar having two poles of equal and opposite pole strengths separated by certain distance (2l).
In simple words: A bar magnet is a rectangular piece of magnetic material with two poles of equal and opposite strength (North and South) separated by a specific distance.

🎯 Exam Tip: A concise definition of a bar magnet should include its shape and the presence of two equal and opposite poles.

Question 4. If you freely hang a bar magnet horizontally, in which direction will it become stable?
Answer:
A bar magnet suspended freely in air always aligns itself along geographic N-S direction.
In simple words: A freely suspended bar magnet always aligns itself in a stable position along the Earth's geographic North-South direction, with its North pole pointing towards the geographic North.

🎯 Exam Tip: Understand that a freely suspended magnet aligns itself with the Earth's magnetic field, approximately along the geographic North-South direction.

Try This (Textbook Page No. 221)

Question. You can take a bar magnet and a small compass needle. Place the bar magnet at a fixed position on a paper and place the needle at various positions. Noting the orientation of the needle, the magnetic field direction at various locations can be traced.
Answer:
When a small compass needle is kept at any position near a bar magnet, the needle always aligns itself in the direction parallel to the direction of magnetic lines of force.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक बार चुंबक के चारों ओर चुंबकीय क्षेत्र रेखाओं को ट्रेस करने के लिए एक छोटी कंपास सुई का उपयोग करने की विधि को दर्शाता है। कंपास सुई को चुंबक के पास अलग-अलग बिंदुओं (A, B, C, D) पर रखा गया है, और प्रत्येक बिंदु पर सुई की दिशा चुंबकीय क्षेत्र की दिशा को इंगित करती है, जिससे क्षेत्र रेखाओं का पता चलता है।
Hence, by placing it at different positions, A, B, C, D,... as shown in the figure, the direction of magnetic lines of force can be traced. The direction of magnetic field will be a tangent at that point.
In simple words: A compass needle, when placed near a bar magnet, aligns itself tangentially to the magnetic field lines at that point, allowing us to map the magnetic field direction around the magnet.

🎯 Exam Tip: This activity demonstrates how a compass needle acts as a detector for magnetic field direction, aligning itself tangentially to the field lines at any given point.