Q1. What is the primary component of natural magnets like magnetite?
a) Copper
b) Aluminium
c) Iron
d) Zinc
Answer: c) Iron
Explanation: Magnetite, a natural magnet, contains iron as its primary component. This is what gives magnetite, and natural magnets in general, their magnetic properties.
Q2. Which of these items is NOT typically attracted to a magnet?
a) A steel spoon
b) A wooden pencil
c) An iron nail
d) A nickel coin
Answer: b) A wooden pencil
Explanation: Magnets attract materials that are magnetic, such as iron, nickel, and cobalt. A wooden pencil is non-magnetic and would not be attracted to a magnet.
Q3. What did the ancient shepherd named Magnes discover about his stick?
a) It could float in water
b) It attracted pieces of paper
c) It stuck to a rock due to a magnetic attraction
d) It repelled animals
Answer: c) It stuck to a rock due to a magnetic attraction
Explanation: According to the story, the shepherd Magnes discovered that the iron tip of his stick was attracted to a rock on the mountainside, which was a natural magnet. This is one of the earliest known discoveries of magnetic properties.
Q4. In the experiment with a suspended bar magnet, the magnet always comes to rest in which direction?
a) East-West
b) North-South
c) It varies each time
d) Upwards-Downwards
Answer: b) North-South
Explanation: A freely suspended magnet always aligns itself in the North-South direction. This property of magnets is used in compasses for navigation.
Q5. Which of these materials is not attracted to a magnet?
a) Iron
b) Nickel
c) Cobalt
d) Plastic
Answer: d) Plastic
Explanation: Plastic is a non-magnetic material and does not get attracted to magnets. Iron, nickel, and cobalt are examples of magnetic materials that are attracted to magnets.
Q6. What is the correct way to store bar magnets to maintain their magnetism?
a) By heating them regularly
b) By keeping them in water
c) By placing them in pairs with unlike poles on the same side
d) By isolating them from all other metals
Answer: c) By placing them in pairs with unlike poles on the same side
Explanation: To maintain their magnetism and prevent them from becoming weak, bar magnets should be stored in pairs with their unlike poles on the same side. They should also be separated by a piece of wood, and soft iron should be placed across their ends.
Q7. How can a simple iron bar be transformed into a magnet?
a) By cooling it to very low temperatures
b) By striking it with another magnet
c) By rubbing it with a bar magnet in one direction several times
d) By painting it with magnetic paint
Answer: c) By rubbing it with a bar magnet in one direction several times
Explanation: An iron bar can be magnetized by rubbing it with one pole of a bar magnet in one direction repeatedly. This aligns the magnetic domains in the iron bar, giving it magnetic properties.
Q8. What happens when the north pole of one magnet is brought near the south pole of another magnet?
a) They repel each other
b) They attract each other
c) No reaction occurs
d) They become demagnetized
Answer: b) They attract each other
Explanation: Opposite poles of magnets (north and south) attract each other. This is a fundamental property of magnets where unlike poles attract.
Q9. What kind of materials can be detected in soil using a magnet?
a) Plastic particles
b) Glass fragments
c) Iron filings
d) Wood chips
Answer: c) Iron filings
Explanation: Magnets can attract iron filings present in the soil. This is used to detect the presence of iron particles in soil samples.
Q10. What is the purpose of the statue with an extended arm on Emperor Hoang Ti’s chariot?
a) To show the direction of the wind
b) To always point towards South for navigation
c) To ward off evil spirits
d) To indicate the presence of magnetic fields
Answer: b) To always point towards South for navigation
Explanation: The statue on Emperor Hoang Ti’s chariot was designed to always point towards South. This was an early use of magnetism for navigation, as the statue probably contained a magnetic element that aligned with the Earth’s magnetic field.
Q11. In the compass making activity, what is used to make the compass needle?
a) A piece of wood
b) A glass rod
c) An iron needle
d) A plastic straw
Answer: c) An iron needle
Explanation: An iron needle is magnetized and used as the compass needle. When floated on water, it aligns with the Earth’s magnetic field, indicating the North-South direction.
Q12. What is the effect of heating or hammering on a magnet?
a) It increases its magnetic strength
b) It has no effect
c) It can cause the magnet to lose its magnetic properties
d) It changes the magnet’s polarity
Answer: c) It can cause the magnet to lose its magnetic properties
Explanation: Heating, hammering, or dropping a magnet can cause it to lose its magnetic properties. These actions can misalign the magnetic domains within the magnet, weakening its magnetic field.
Q13. What type of magnet is created by humans and not found naturally?
a) Natural magnet
b) magnetite
c) Artificial magnet
d) Permanent magnet
Answer: c) Artificial magnet
Explanation: Artificial magnets are those created by humans, as opposed to natural magnets like magnetite. They are typically made by magnetizing materials like iron or steel.
Q14. In the ‘Magnes walk’ activity, what does the ‘Magnes stick’ pick up from the ground?
a) Leaves and twigs
b) Plastic pieces
c) Magnetic materials
d) All kinds of dirt
Answer: c) Magnetic materials
Explanation: During the ‘Magnes walk’ activity, the ‘Magnes stick’, which is a stick with a magnet attached, picks up magnetic materials like iron filings or small metal objects from the ground.
Q15. Why are the north (N) and south (S) poles marked on a magnet?
a) To indicate the strongest points of the magnet
b) To show the direction of magnetic field lines
c) For decorative purposes
d) To distinguish between the two different ends of the magnet
Answer: d) To distinguish between the two different ends of the magnet
Explanation: The north (N) and south (S) poles are marked on a magnet to distinguish between its two different ends. Each pole exhibits distinct magnetic behaviors, such as attraction or repulsion with other magnets.
Q16. What will happen if a magnet is brought near a compass?
a) The compass needle will point towards the magnet
b) The compass will lose its magnetic properties
c) The compass needle will spin continuously
d) The compass will become a temporary magnet
Answer: a) The compass needle will point towards the magnet
Explanation: When a magnet is brought near a compass, the compass needle, which is itself a small magnet, will align itself towards the external magnet due to magnetic attraction or repulsion, depending on the poles facing each other.
Q17. What did Paheli and Boojho observe with a magnet and iron filings?
a) Iron filings did not stick to the magnet at all
b) Iron filings formed a pattern around the magnet
c) Iron filings repelled the magnet
d) The magnet lost its magnetic properties
Answer: b) Iron filings formed a pattern around the magnet
Explanation: When Paheli and Boojho used a magnet with iron filings, they observed that the filings formed a pattern around the magnet, particularly clustering more densely at the poles, demonstrating the magnetic field lines.
Q18. What material is likely found in the part of a pencil sharpener that is attracted to a magnet?
a) Plastic
b) Wood
c) Iron or steel
d) Rubber
Answer: c) Iron or steel
Explanation: The part of a pencil sharpener that is attracted to a magnet is likely made of a magnetic material such as iron or steel. Even though the body of the sharpener is plastic, the blade or other components that attract the magnet would be metallic.
Q19. What is the main property of a material that is classified as magnetic?
a) It can be stretched into thin wires.
b) It is always shiny and silver in color.
c) It gets attracted towards a magnet.
d) It can float on water.
Answer: c) It gets attracted towards a magnet.
Explanation: The defining property of a magnetic material is its ability to be attracted towards a magnet. This includes materials like iron, nickel, and cobalt.
Q20. How do magnets behave when similar poles are brought close to each other?
a) They attract each other strongly.
b) They do not interact at all.
c) They repel each other.
d) They become demagnetized.
Answer: c) They repel each other.
Explanation: When similar poles (either both north or both south) of two magnets are brought close together, they repel each other. This is a basic property of magnets where like poles repel and unlike poles attract.
Q21. What is the purpose of using iron filings in magnet-related experiments?
a) To increase the magnet’s strength.
b) To create a temporary magnet.
c) To visualize the magnetic field lines.
d) To test the magnet’s polarity.
Answer: c) To visualize the magnetic field lines.
Explanation: Iron filings are used in magnet-related experiments to visualize the magnetic field lines around a magnet. The filings align along the magnetic field lines, allowing us to see the pattern of the field.
Q22. What role does magnetism play in a compass?
a) It holds the needle in place.
b) It allows the needle to point towards the geographic North Pole.
c) It makes the compass needle glow in the dark.
d) It ensures the compass always points to the strongest magnetic field.
Answer: b) It allows the needle to point towards the geographic North Pole.
Explanation: In a compass, magnetism allows the needle, which is a small magnet, to align with the Earth’s magnetic field. This alignment causes the needle to point towards the geographic North Pole.
Q23. In the chapter, what was the method suggested to create your own magnet?
a) Placing an iron bar in a strong magnetic field.
b) Striking an iron bar repeatedly with a hammer.
c) Rubbing an iron bar with a magnet in a single direction multiple times.
d) Heating an iron bar to a very high temperature.
Answer: c) Rubbing an iron bar with a magnet in a single direction multiple times.
Explanation: The chapter suggests creating your own magnet by rubbing an iron bar with one pole of a bar magnet in one direction repeatedly. This process aligns the magnetic domains in the iron bar, thus magnetizing it.
Q24. Which materials are generally non-magnetic?
a) Iron, nickel, and cobalt.
b) Copper, aluminum, and plastic.
c) Gold, silver, and platinum.
d) Steel, zinc, and brass.
Answer: b) Copper, aluminum, and plastic.
Explanation: Copper, aluminum, and plastic are examples of non-magnetic materials. They do not get attracted to magnets. Materials like iron, nickel, and cobalt are magnetic.
Q25. What is the effect of dropping a magnet from a height?
a) It increases its magnetic strength.
b) It has no effect on its magnetic properties.
c) It can cause the magnet to lose some of its magnetic properties.
d) It reverses the poles of the magnet.
Answer: c) It can cause the magnet to lose some of its magnetic properties.
Explanation: Dropping a magnet from a height can cause it to lose some of its magnetic properties. This is because the shock from the impact can disrupt the alignment of the magnetic domains within the magnet.
Q26. Why should magnets be stored with a piece of wood between them?
a) To prevent them from losing their magnetic properties.
b) To avoid them sticking to metal surfaces.
c) To keep them from attracting unwanted metal objects.
d) To ensure they do not repel each other.
Answer: a) To prevent them from losing their magnetic properties.
Explanation: Storing magnets with a piece of wood between them helps maintain their magnetic strength. This arrangement prevents the magnets from demagnetizing each other, ensuring they retain their magnetic properties.
Q27. What is the main use of a compass?
a) To measure distances.
b) To determine the direction of magnetic fields.
c) To find geographical directions.
d) To create temporary magnets.
Answer: c) To find geographical directions.
Explanation: The primary use of a compass is to find geographical directions. The magnetized needle of the compass aligns with the Earth’s magnetic field, pointing towards the geographic North, thereby indicating direction.
Q28. Which end of a freely suspended magnet points towards the geographic North?
a) The lighter end.
b) The end marked with a red dot.
c) The North-seeking end or the North pole.
d) The South-seeking end or the South pole.
Answer: c) The North-seeking end or the North pole.
Explanation: In a freely suspended magnet, the North-seeking end, also known as the North pole, aligns itself and points towards the geographic North. This is a fundamental property of magnets and the basis for using compasses for navigation.
Q29. What happens to the poles of a bar magnet if it is broken in half?
a) Each half loses its magnetic property.
b) Only one half remains magnetic.
c) Each half becomes an individual magnet with north and south poles.
d) The poles reverse in each half.
Answer: c) Each half becomes an individual magnet with north and south poles.
Explanation: If a bar magnet is broken in half, each half becomes a separate magnet, with its own north and south poles. The magnetic property is inherent in the material of the magnet and does not depend on its size.
Q30. What is the main characteristic of a natural magnet like magnetite?
a) It can be easily demagnetized.
b) It has only one magnetic pole.
c) It has the property of attracting pieces of iron.
d) It always points towards the East-West direction.
Answer: c) It has the property of attracting pieces of iron.
Explanation: A natural magnet like magnetite has the characteristic property of attracting pieces of iron. This property was first observed in naturally occurring rocks and led to the discovery of magnetism.
Q31. What is the primary difference between a bar magnet and an electromagnet?
a) A bar magnet is always on, while an electromagnet can be turned on and off.
b) A bar magnet attracts all metals, but an electromagnet only attracts iron.
c) Bar magnets are natural, while electromagnets are artificial.
d) Electromagnets are always stronger than bar magnets.
Answer: a) A bar magnet is always on, while an electromagnet can be turned on and off.
Explanation: The primary difference between a bar magnet and an electromagnet is that a bar magnet has a permanent magnetic field, while an electromagnet’s magnetic field can be activated and deactivated with electricity.
Q32. What kind of objects did Paheli and Boojho collect to test with their ‘Magnes stick’?
a) Metallic and non-metallic objects from their surroundings.
b) Only objects made of iron and steel.
c) Objects that are naturally magnetic.
d) Items that are known to be non-magnetic.
Answer: a) Metallic and non-metallic objects from their surroundings.
Explanation: Paheli and Boojho collected various objects of day-to-day use, both metallic and non-metallic, from their surroundings to test with their ‘Magnes stick’, which is a magnet attached to a stick.
Q33. In the ancient story about the shepherd named Magnes, what did the iron tip of his stick attach to?
a) A wooden rock
b) A piece of cloth
c) A magnetic rock
d) A metallic gate
Answer: c) A magnetic rock
Explanation: According to the story, the iron tip of the shepherd Magnes’s stick attached to a magnetic rock on the mountainside. This story is often cited as an early discovery of natural magnets.
Q34. What is the significance of the extended arm of the statue in Emperor Hoang Ti’s chariot?
a) It was used to measure the speed of the chariot.
b) It acted as a weather vane.
c) It pointed towards South for navigation.
d) It was a symbol of the Emperor’s authority.
Answer: c) It pointed towards South for navigation.
Explanation: The extended arm of the statue in Emperor Hoang Ti’s chariot was significant for navigation as it always pointed towards South. This was due to a magnetic element in the statue that aligned with Earth’s magnetic field.
Q35. What did the experiment with iron filings and a bar magnet demonstrate?
a) The magnetic field is strongest at the center of the magnet.
b) Iron filings are repelled by magnets.
c) The magnetic field is strongest at the poles of the magnet.
d) Bar magnets only attract iron filings at one end.
Answer: c) The magnetic field is strongest at the poles of the magnet.
Explanation: The experiment with iron filings and a bar magnet demonstrated that the magnetic field is strongest at the poles of the magnet. This is evident from the concentration of iron filings at the ends of the magnet.
Q36. Why should magnets be kept away from electronic devices like TVs and mobiles?
a) Magnets can disrupt the functioning of these devices.
b) Magnets can erase the data stored in these devices.
c) Magnets can cause these devices to overheat.
d) Both a and b.
Answer: d) Both a and b.
Explanation: Magnets should be kept away from electronic devices like TVs and mobiles because they can disrupt the functioning of these devices and potentially erase or corrupt the data stored in them, especially in devices that use magnetic storage media.