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

Which of the following statements is not true?

  1. When a piece of magnetic material comes close to a magnet, temporary magnetic poles are created at its end.

  2. The region around a magnet where its effects can be felt, is called the magnetic pole.

  3. Like poles repel and unlike poles attract.

  4. A bar magnet when suspended comes to rest along the North - South direction.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is correctly identified as NOT true. The region around a magnet where its effects can be felt is called the magnetic FIELD, not the magnetic pole. Poles are specific points (North and South) at the ends of a magnet where the magnetic force is strongest. The field is the entire region of magnetic influence extending beyond just the poles.

Multiple choice

Which of the following is not true about an electromagnet?

  1. This type of magnet is made by using an electric current.

  2. The core of an electromagnet is made of iron.

  3. They are used in electric bells.

  4. An electromagnet is a permanent magnet.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Electromagnet is not a permanent magnet. The magnetism is not retained once the current is switched off.

Multiple choice

Which of the following materials is best suited as the core of an electromagnet?

  1. Steel

  2. Alnico

  3. Magnetite

  4. Iron
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Iron (specifically soft iron) is the best core material for electromagnets. It has very high magnetic permeability, meaning it strongly concentrates magnetic field lines. Iron magnetizes and demagnetizes rapidly when current is turned on/off. Steel retains residual magnetism (becomes permanent), alnico is designed for permanent magnets, and magnetite is a naturally magnetic mineral.

Multiple choice

What will happen, if a magnet is cut into two pieces of equal length?

  1. Both pieces will lose their magnetism.

  2. One piece will act as North Pole and the other as South Pole.

  3. Both pieces will behave as complete magnets.

  4. One of the pieces will lose its magnetism.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cutting a magnet produces two complete magnets, each with its own north and south poles. This happens because magnetic poles always exist in pairs - you cannot isolate a single pole. Each piece retains its magnetic properties.

Multiple choice

When a bar magnet immersed in a heap of iron fillings is taken out, it is observed that iron fillings stick to the surface of the bar magnet. The iron fillings would be observed to

  1. stick uniformly throughout the surface of the bar magnet

  2. stick randomly on the surface of bar magnet

  3. have maximum concentration at the two ends of the bar magnet

  4. have maximum concentration slightly away from the two ends of the bar magnet
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The magnetic field of a bar magnet is strongest at its poles (the two ends). This is why iron filings cluster most densely at the ends - they are attracted to the regions of maximum magnetic field strength, not the middle.

Multiple choice

What is the role of commutator rings in an electric motor?

  1. To increase the strength of current flowing

  2. To reverse the direction of current flowing

  3. To increase the strength of magnetic field

  4. To decrease the strength of current flowing

  5. -
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This is the correct answer. The function of a commutator ring is to reverse the direction of current flowing.

Multiple choice

Which of the following statements about an electromagnet is not true?

  1. It is a temporary magnet.

  2. It produces a much weaker field than a permanent magnet.

  3. Its strength can be easily varied.

  4. Its polarity can be reversed.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Electromagnets can produce a very strong magnetic field. Permanent magnets produce a much weaker field than electromagnets.