Exploring Magnets Part 4: MCQs (Q76–Q100)
Part 4 — Questions 76–100 (Advanced applications, misconceptions, revision & mixed practice)
76. Which of the following statements is FALSE?
A. Magnetic field lines never cross each other
B. Magnetic monopoles (single isolated poles) are commonly found in everyday magnets ← Correct answer: B
C. Field lines form closed loops
D. Density of lines indicates field strength
Explanations:
A/C/D) True statements.
B) False — magnetic monopoles are not observed in normal magnets.
77. Which of the following items can disturb a compass reading the most?
A. A wooden table far away
B. A strong magnet or iron object close to the compass ← Correct answer: B
C. Paper notes on the table far away
D. A plastic toy across the room
Explanations:
A/C/D) Minimal effect.
B) Correct — local magnetic sources override Earth’s field locally.
78. Which is a correct way to store magnets so they remain strong?
A. Throw them randomly in a drawer with no contact
B. Keep opposite poles of two magnets together or use keeper bars to prevent demagnetisation ← Correct answer: B
C. Keep them near hot stove always
D. Hit them frequently to keep them lively
Explanations:
A/C/D) Not ideal—heat/shock demagnetise.
B) Correct — attaching opposite poles reduces external field and preserves magnetism.
79. A student brings a copper coin near a magnet and notes no attraction. This suggests copper is
A. A strong ferromagnetic material
B. Non-magnetic ← Correct answer: B
C. Made of iron only
D. Highly magnetic but invisible
Explanations:
A/C/D) Incorrect.
B) Correct — copper is not attracted by typical magnets.
80. Which of the following pairs are both magnetic?
A. Wood and glass
B. Iron and nickel ← Correct answer: B
C. Plastic and cotton
D. Paper and rubber
Explanations:
A/C/D) Non-magnetic pairs.
B) Correct — iron and nickel are ferromagnetic.
81. Which statement best explains why a compass needle points north even indoors?
A. Interiors are colder than outdoors
B. Earth’s magnetic field permeates the region so the needle aligns with it unless disturbed ← Correct answer: B
C. Compass depends on light only
D. The needle’s battery powers it to point north
Explanations:
A/C/D) Incorrect.
B) Correct — Earth’s field is present everywhere; local ferrous objects may disturb it.
82. Which of these magnets would produce the strongest magnetic field in the gap between its poles?
A. A very long bar magnet with poles far apart
B. A horseshoe magnet with poles close together ← Correct answer: B
C. A plastic rod painted like a magnet
D. A tiny magnet buried in sand far away
Explanations:
A/C/D) Less effective.
B) Correct — bringing poles close concentrates field.
83. Which phenomenon explains how electricity can be generated using magnets?
A. Chemical reaction only
B. Electromagnetic induction (Faraday’s law) ← Correct answer: B
C. Photosynthesis only
D. Wind only
Explanations:
A/C/D) Not the mechanism.
B) Correct — changing magnetic flux induces current in coils (principle of generators).
84. A non-magnetic nail is placed between poles of a strong magnet. After a while the nail is found to stick to the magnet. This happens because the nail has become
A. Permanently heated to glue itself
B. Induced magnet (temporary) due to alignment of domains ← Correct answer: B
C. Changed into wood
D. Disappeared
Explanations:
A/C/D) Not true.
B) Correct — induction magnetises the nail, causing attraction.
85. Which of the following is a real-life example of magnetic separation?
A. Separating sugar from tea
B. Removing iron clips from cereal using magnets ← Correct answer: B
C. Sorting fruits by colour
D. Filtering water with paper only
Explanations:
A/C/D) Not magnetic separation.
B) Correct — magnets used to remove metallic impurities from food/grain.
86. Which of the following statements is CORRECT?
A. Magnets attract only iron and no other element ever
B. Magnets strongly attract iron, cobalt and nickel; some alloys and steels also are magnetic ← Correct answer: B
C. All types of stainless steel are highly magnetic always
D. Wood is usually magnetic
Explanations:
A/C/D) Incorrect generalizations.
B) Correct — common ferromagnetic metals and some steel alloys show magnetism.
87. The reason a compass needle aligns along the magnetic field is that the needle is
A. A small magnet and experiences torque aligning it with the field
B. Made of plastic painted metallic
C. Attracted to the Moon always
D. Stationary due to glue
Correct answer: A ← Correct answer: A
Explanations:
A) Correct — magnetic torque aligns needle with field lines.
B/C/D) Incorrect.
88. Which of the following will experience the greatest magnetic force from a bar magnet?
A. Aluminium foil at 10 cm away
B. Iron nail at 1 cm from the pole ← Correct answer: B
C. Rubber band touching the magnet
D. Cardboard piece near the magnet
Explanations:
A/C/D) Non-magnetic or weakly magnetic materials.
B) Correct — iron close to the pole sees strong force.
89. Electromagnets are preferred in many machines because they
A. Are always cold even under heavy use
B. Can be switched on and off by controlling the electric current ← Correct answer: B
C. Last forever without power supply
D. Produce light as primary function
Explanations:
A/C/D) Not main reasons.
B) Correct — controllable magnetism is key advantage.
90. Which of the following would be the best material for making a magnetic core of an electromagnet?
A. Glass
B. Soft iron ← Correct answer: B
C. Wood
D. Plastic
Explanations:
A/C/D) Non-magnetic materials.
B) Correct — soft iron becomes strongly magnetised but loses magnetism when current removed (desirable property).
91. When field lines from two magnets in opposite orientation meet, they tend to
A. Cross each other freely
B. Attract each other creating strong field between opposite poles ← Correct answer: B
C. Make the magnets disappear
D. Turn into sunlight
Explanations:
A/C/D) Incorrect.
B) Correct — opposite poles attract and field lines connect between them.
92. Which technique is used to magnetise a sewing needle permanently?
A. Painting with oil only
B. Stroking repeatedly in same direction with one pole of a strong magnet and then treating appropriately ← Correct answer: B
C. Putting needle in freezer
D. Leaving needle near loud music
Explanations:
A/C/D) No effect.
B) Correct — stroking aligns domains, and subsequent handling can produce semi-permanent magnetism.
93. A magnetic compass placed at the centre of a loop of current shows no deflection. Why?
A. Current destroys the compass needle permanently
B. If current is zero or symmetric fields cancel, no net field may exist at centre ← Correct answer: B
C. Compass always points East only
D. Compass turns into a wheel
Explanations:
A/C/D) Incorrect.
B) Correct — configuration/zero current can result in no net field at the centre.
94. A bar magnet is suspended at its centre and cut into halves along its length (not across). Each half will have
A. Only a North pole and become non-magnetic at other end
B. Both North and South poles (each half becomes a magnet) ← Correct answer: B
C. No magnetic properties at all
D. Turn into two wooden sticks
Explanations:
A/C/D) Incorrect.
B) Correct — cutting produces smaller magnets each with two poles.
95. Which of the following materials is best for making a permanent magnet?
A. Soft iron (becomes temporary magnet)
B. Hard steel or alloys specially treated (retain magnetism) ← Correct answer: B
C. Glass
D. Pure water
Explanations:
A) Soft iron loses magnetism when external field removed — not ideal for permanent magnets.
B) Correct — hard magnetic materials retain aligned domains as permanent magnets.
C/D) Non-magnetic.
96. The patterns made by iron filings around two like poles (North–North) will show
A. Filings joining in straight lines between the poles (attraction)
B. Lines bending away from each other showing repulsion ← Correct answer: B
C. Filings dissolve into powder and disappear
D. Filings forming perfect circles only
Explanations:
A/C/D) Incorrect.
B) Correct — lines show repulsion with bulging patterns between like poles.
97. What would best describe the relation between electricity and magnetism?
A. They are entirely unrelated phenomena
B. Electric currents produce magnetic fields; changing magnetic fields can induce electric current ← Correct answer: B
C. Magnetism only occurs in sunlight
D. Electricity is created only by rubbing magnets
Explanations:
A/C/D) Incorrect.
B) Correct — fundamental connection (electromagnetism).
98. Which practice can permanently damage a magnet?
A. Storing with pole keepers
B. Heating to high temperature or hammering ← Correct answer: B
C. Keeping in a closed wooden box
D. Placing it on a padded shelf gently
Explanations:
A/C/D) Safe methods.
B) Correct — thermal and mechanical shocks demagnetise magnets.
99. Why do iron filings not show magnetic field inside a closed ferromagnetic ring easily?
A. Field is extremely weak inside such ring or filings arrangement differs
B. Filings hate being inside rings
C. Ring converts field to light
D. Filings are not real metal
Correct answer: A ← Correct answer: A
Explanations:
A) Correct — in closed magnetic circuits, field may be contained so filings outside don’t show obvious external pattern.
B/C/D) Silly/incorrect.
100. Final quick revision — Which one-line statement is MOST accurate?
A. Magnets only attract non-metallic materials
B. Magnets have two poles; like poles repel; unlike poles attract; field lines form closed loops ← Correct answer: B
C. Magnetism stops at the Earth’s surface only
D. All metals are permanently magnetic by default
Explanations:
A/C/D) Incorrect statements.
B) Correct — concise summary of basic magnet rules.