Physics

Magnetism and Electromagnetism

1,019 Questions

This hub provides practice questions on magnetism and electromagnetism. It covers magnetic flux density, electromagnets, magnetic lines of force, and electromagnetic induction. These physics concepts frequently appear in technical and non-technical competitive exams.

Electromagnet coresMagnetic flux densityMagnetic lines of forceElectromagnetic inductionBar magnet propertiesMagnetic materials

Magnetism and Electromagnetism Questions

Multiple choice

Magnetic lines of force ______________.

  1. are closed and continuous curves

  2. travel in the East-West direction

  3. always intersect each other

  4. can travel in any direction

  5. depend upon the shape of magnet
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Magnetic lines of forces are the closed and continuous curve, which travel in the North-South direction and never intersect each other.

Multiple choice

The power of the magnetic force __________.

  1. increases from North pole to South pole

  2. is same all over the magnet

  3. is minimum near its ends and maximum in the middle

  4. decreases from North pole to South pole

  5. maximum near its ends and decreases towards the middle
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Yes, the magnetic forces of a magnet are maximum at poles and decrease towards the middle.

Multiple choice

We can magnetise a magnetic substance without touching it by a magnet by

  1. single touch method

  2. double touch method

  3. magnetic induction

  4. using electric current

  5. using magnetic compass
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using electric current, we can magnetise a magnetic substance without touching it by a magnet. The magnet made by using electric current is called an electromagnet.

Multiple choice

A magnetic keeper is

  1. a person who looks after magnets

  2. a piece of aluminium that is placed at the ends of the two bar magnets

  3. a piece of steel that is placed at the ends of the two bar magnets

  4. a piece of soft iron that is placed at the ends of the two bar magnets

  5. a box in which magnet is kept
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To avoid de-magnetisation, we arrange two bar magnets in the form of pairs with opposite poles facing each other. At either end of the pair of magnets, two soft iron bars are placed, which are called magnetic keepers.

Multiple choice

Like gases, plasmas do not have a definite shape or volume. But unlike gases,

  1. plasma state is reached at a very low temperature

  2. plasma state is electrically conductive

  3. plasmas produce magnetic field

  4. Both (2) and (3)

  5. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Plasma is considered as the fourth state of matter. Plasmas are similar to gases. All stars are made of plasma. Because of the presence of plasma, stars glow. Plasma is formed because of nuclear fusion in stars.

Multiple choice

Choose the correct option.

  1. Attraction precedes induction in magnetism.

  2. Induction precedes repulsion in magnetism.

  3. Iinduction precedes attraction in magnetism.

  4. All are incorrect
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When a magnet approaches a magnetic material, induction occurs first (temporary magnetic poles form in the material due to the magnetic field), and then attraction follows between the induced poles and the magnet's poles. This sequence is fundamental to magnetic phenomena.

Multiple choice

Which of the following statements is false?

  1. An object which attracts other objects made of magnetic materials is called a magnet.

  2. All magnets are made of iron.

  3. Magnets do not attract stainless steel.

  4. A magnet has two poles.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Because all magnets are not made of iron, some are made of alloy of aluminium, nickel and cobalt.

Multiple choice

When a bar magnet is suspended, it always points in the __________ direction.

  1. North-East

  2. South-West

  3. North-South

  4. East-West
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A freely suspended bar magnet always aligns itself in the North-South direction because Earth itself acts as a giant magnet. The magnet's north pole points towards geographic North (which is actually magnetic south), and the south pole points towards geographic South. This directional property is why compasses work.

Multiple choice

Which of the following statements is not true?

  1. A magnet created by an electric current is called a diamagnet.

  2. Repulsion is a sure test for magnetism than attraction.

  3. Permanent magnets tend to lose its magnetism gradually, if the poles are left open.

  4. A compass uses the directional property of a permanent magnet.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The statement is correctly identified as NOT true. Magnets created by electric current are called electromagnets, NOT diamagnets. Diamagnetism is a completely different property where materials weakly repel magnetic fields (like copper or bismuth). Repulsion IS a better test of magnetism than attraction because any unmagnetized magnetic material will be attracted to a magnet, but only like poles repel.

Multiple choice

Which of the following, best describes the field due to a magnet?

  1. Two regions near to the poles

  2. Region lying between the poles

  3. Region where its effect can be felt

  4. Region where it aligns itself along the North-South direction
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A magnetic field is defined as the region around a magnet where its magnetic influence can be detected or felt - where a magnetic material or another magnet would experience force. This field extends beyond just the space between the poles and encompasses the entire 3D space surrounding the magnet.

Multiple choice

Which of the following can be used as a magnetic keeper?

  1. Stainless steel

  2. Iron

  3. Alnico

  4. Wood
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Iron is the best material for magnetic keepers. A magnetic keeper (or magnet keeper) is a soft iron piece placed across the poles of a horseshoe magnet to preserve its strength. Soft iron has high magnetic permeability, allowing it to provide a low-reluctance path for magnetic flux, preventing self-demagnetization. Stainless steel is not magnetic enough, alnico is already a magnet, and wood is non-magnetic.

Multiple choice

Permanent magnets can be damaged by which of the following?

  1. Exposure to heat

  2. Hammering

  3. Dropping form a height

  4. All of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

All three actions can damage permanent magnets. Heat increases molecular motion, randomizing magnetic domain alignment (Curie temperature). Hammering or dropping physically disrupts the alignment of magnetic domains in the material. All these methods can weaken or completely destroy a permanent magnet's strength.