Physics

Magnetism and Electromagnetism

1,011 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 would be most powerful electromagnet?

  1. Air

  2. Copper

  3. Steel

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

Soft iron is a ferromagnetic material that is easily magnetized and demagnetized, making it ideal for creating strong temporary electromagnets. Steel retains magnetism, making it better for permanent magnets.

Multiple choice

Unlike poles of a magnet

  1. Neither attract nor repel

  2. Attract each other

  3. Sometimes repel sometimes attract

  4. Repel each other
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Like poles always repel and unlike poles always attract.

Multiple choice

Substances showing permanent magnetism are known as

  1. paramagnetic materials

  2. ferrimagnetic substances

  3. ferromagnetic substances

  4. anti-ferromagnetic substances

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

These substances show permanent magnetism even when the magnetic field is removed. For example,  FeO and CrO2 Fe, Co, Ni show ferromagnetism even at room temperature.

Multiple choice

The substances having zero net magnetic moment are known as

  1. diamagnetic materials

  2. paramagnetic materials

  3. ferromagnetic substances

  4. anti-ferromagnetic substances
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Anti-ferromagnetic substances are expected to possess paramagnetism or ferromagnetism on the basis of unpaired electrons present in them but actually they possess zero net magnetic moment. This is because of the alignment of dipoles is in a compensatory way so as to give a net zero dipole moment, then we get antiferromagnetic substances (MnO).

Multiple choice

On which principle does a tape recorder function?

  1. Electromagnetic induction

  2. Electrovalency

  3. Gay Lussac's Law of combining volumes

  4. Boyle's Law
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A tape recorder functions by converting electrical signals into magnetic patterns on a tape using electromagnetic induction, and vice versa during playback.

Multiple choice

The fluid capable of changing its properties by applying an electric field or a magnetic field is

  1. smart fluid

  2. magnetorheological fluid

  3. electrorheological fluid

  4. ferrofluid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A smart fluid is a fluid whose properties (for example the viscosity) can be changed by applying an electric field or a magnetic field. The most developed smart fluids today are fluids whose viscosity increases when a magnetic field is applied.

Multiple choice

A freely suspended bar magnet always points in __________ direction.

  1. north- east

  2. south-west

  3. north-south

  4. south-east

  5. none of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yes, it is the correct answer. A freely suspended magnet always comes to rest in the north-south direction. Earth is a giant magnet and its magnetic south pole is towards the geographic north pole. As opposite poles of two magnets attract each other, therefore the north pole of the bar magnet  points in the direction of the geographic north pole (magnetic south pole of the earth) and south pole of the bar magnet towards the geographic south pole of the earth (magnetic north pole of the earth).