1. Which of the following materials cannot be magnetized?
Answer:
Explanation:
Glass is a non-magnetic material and cannot be magnetized. Iron, Cobalt, and Nickel are ferromagnetic materials and can be magnetized.
2. Magnetic lines of force inside a bar magnet are directed:
Answer:
Explanation:
Inside a bar magnet, magnetic lines of force run from the South pole to the North pole.
3. A magnetic substance that retains its magnetism after being removed from a magnetic field is said to have:
Answer:
Explanation:
Retentivity is the ability of a magnetic substance to retain its magnetism after being removed from a magnetic field.
4. Earth's magnetic field originates due to:
Answer:
Explanation:
Earth's magnetic field is believed to originate from the movement of charged particles, primarily iron and nickel, in its liquid outer core.
5. The phenomenon of a substance being weakly repelled by a magnetic field is called:
Answer:
Explanation:
Diamagnetic substances are weakly repelled by a magnetic field. They have no unpaired electrons and do not retain any magnetism when the external field is removed.
6. Which of the following elements is ferromagnetic at room temperature?
Answer:
Explanation:
Iron is a ferromagnetic material at room temperature, meaning it can be magnetized or attracted to magnets.
7. A freely suspended magnet always points:
Answer:
Explanation:
A freely suspended magnet always aligns itself in the North-South direction due to Earth's magnetic field.
8. Which of the following is true for magnetic field lines?
Answer:
Explanation:
Magnetic field lines always form closed loops, originating from the North pole and ending at the South pole of a magnet.
9. Curie temperature is the temperature:
Answer:
Explanation:
Curie temperature is the critical point above which a ferromagnetic material becomes paramagnetic and loses its ferromagnetic properties.
10. Temporary magnets are made of materials with:
Answer:
Explanation:
Temporary magnets are made of materials with low coercivity and low retentivity, meaning they get magnetized easily but also lose their magnetism quickly.
11. The magnetic properties of a substance are due to:
Answer:
Explanation:
The magnetic properties of a substance are primarily due to the motion of electrons, especially their spin.
12. Which of the following devices is based on the principle of mutual induction?
Answer:
Explanation:
A transformer operates on the principle of mutual induction.
13. The region around a magnet where its influence can be experienced is called:
Answer:
Explanation:
The region around a magnet where its magnetic effect can be felt or experienced is called a magnetic field.
14. Magnetite is another name for:
Answer:
Explanation:
Magnetite is a naturally occurring form of iron oxide (Fe₃O₄) and is one of the earliest known types of magnets.
15. The end of a magnet that points toward the geographical north when suspended freely is:
Answer:
Explanation:
A freely suspended magnet's south pole will point towards the geographical north due to Earth's magnetic field.
16. Materials that have unpaired electrons and are weakly attracted by a magnet are:
Answer:
Explanation:
Paramagnetic materials have unpaired electrons and are weakly attracted by a magnet.
17. The ability of a substance to get magnetized is called:
Answer:
Explanation:
Susceptibility measures how much a material will become magnetized in an external magnetic field.
18. Which of the following materials has the highest permeability?
Answer:
Explanation:
Iron has a high permeability and can be easily magnetized.
19. In a solenoid, the magnetic field is:
Answer:
Explanation:
In a solenoid, the magnetic field is strongest at its center and weaker at its ends.
20. Which of the following is not a property of magnetic field lines?
Answer:
Explanation:
Magnetic field lines cannot be isolated. They always form closed loops.