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.

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Magnetism and Electromagnetism Questions

Multiple choice physics motion, force and speed contact and non-contact forces comparing force in magnetic, electric and gravitational fields identifying forces

Magnetic force is a non contact force because for magnetic force to apply

  1. the bodies have to be in contact.

  2. the bodies need not be in contact.

  3. the bodies may or may not be in contact.

  4. none of these.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Magnetic force, electric force and gravitational forces are non contact forces because for these forces to apply, the bodies need not be in contact (physically touch) with each other.

Multiple choice chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

Magnetic separation is a process in which magnetically susceptible material is extracted from a mixture using a:

  1. Frictional force

  2. Gravitational force

  3. Both a and b

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

Magnetic separation is a process in which magnetically susceptible material is extracted from a mixture using a magnetic force. This separation technique can be useful in mining iron as it is attracted to a magnet.

Multiple choice chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

A ferromagnetic substance becomes a permanent magnet when it is placed in a magnetic field because

  1. all the domains get oriented in the direction of magnetic field

  2. all the domains get oriented in the direction opposite to the direction of magnetic field

  3. domains get oriented randomly

  4. domains are not affected by magnetic field
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Ferromagnetic materials contain magnetic domains. When placed in an external magnetic field, these domains align with the field, resulting in a net magnetic moment and permanent magnetization.

Multiple choice chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

Iron sulphide is not attracted towards magnet whereas its element is attracted towards magnet why?

  1. Properties of compound are similar to the properties of its constituents

  2. Properties of compound are different to the properties of its constituents

  3. Compounds are made up of mixtures

  4. None of above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Iron sulphide is not attracted towards magnet whereas its element (iron) is attracted towards magnet. This suggests that properties of compound are different to the properties of its constituents. In words, magnetic iron on chemical combination with sulphur, gives non magnetic iron sulphide.

Multiple choice chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

A mixture of ____________ can be separated by magnetic attraction.

  1. iron and steel

  2. copper and steel

  3. copper and tin

  4. sand and tn
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
A mixture of sand and tin can be separated by magnetic attraction.
Sand is magnetic and tin is non magnetic. For the mixture to be separated by magnetic attraction, one component should be magnetic whereas remaining components should be non magnetic.
Multiple choice chemistry mix and separate dry methods of separation process of separating components of a mixture method of separation

The process in which magnetically susceptible material is extracted from a mixture using a magnetic force is called:

  1. ferromagnetic separation

  2. magnetic separation

  3. crystallisation

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

Magnetic separation is a process in which magnetically susceptible material is extracted from a mixture using a magnetic force. This separation technique can be useful in mining iron as it is attracted to a magnet.

Multiple choice torque on a dipole in a uniform electric field electric dipole electric charges and fields electrostatics physics

An electric dipole placed with its axis in the direction of a uniform electric field experiences:

  1. a force but not torque

  2. a torque but no force

  3. a force as well as a torque

  4. neither a force nor a torque
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total force of on diopole $= E\ q +E( -q )$ $= 0$
We know,
 Torque $= \vec{P} \times \vec{E}$
but axis of dipole is in the direction of electric field
$\therefore \tau = P.E\ sin\ 0$
$\therefore \tau = 0$
$\therefore $ No torque, No force is acting on dipole

Multiple choice torque on a dipole in a uniform electric field electric dipole electric charges and fields electrostatics physics

An electric dipole is kept in the surrounding of another dipole, it experiences

  1. a force and a torque

  2. a force but not a torque

  3. a force but not necessarily a torque

  4. neither a force nor a torque
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The electric field produced by a dipole is non-uniform. Therefore, another dipole placed in this field will experience a non-zero net force and a torque, depending on its orientation and position.

Multiple choice torque on a dipole in a uniform electric field electric dipole electric charges and fields electrostatics physics

An electric dipole is placed in non-uniform electric field, then it experiences

  1. only torque

  2. force and torque

  3. only force

  4. neither force nor torque
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Given an electric dipole placed in a non-uniform electric field. An electric dipole always experiences a torque when placed in uniform as well as non-uniform electric field. But in non-uniform electric field, dipole will also experience net force of attraction. So the electric dipole in non-uniform electric field experiences both torque and force.

Multiple choice physics magnetic effect of electric current oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

Which of the following is/are correct?

  1. Electric current can produce a magnetism

  2. Due to change in current the magnetic strength changes

  3. Magnetic strength of a magnet is independent of the number of turn in the current carrying coil

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

I)According to Oersted experiment electric current can produce magnetism.

iI)Magnetic induction $B \alpha I$
If current changes the strength $B$ changes.
iiI)For circular coil magnetic field $B$ due to single ring $B=\dfrac{\mu _0 i}{2r}$
If magnet contain n turn then its strength is $B _2=nB$
But if current carrying coil have $n _2$ turn then strength doesn't change.
$B _2=nB$
Hence all options are correct.

Multiple choice physics magnetic effect of electric current oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

Electromagnet can be formed due to which of the following?

  1. Heating effect of current

  2. Magnetic effect of current

  3. Chemical effect of current

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Electromagnets are formed by passing an electric current through a wire coiled around the substance with iron core. The electric current generates a magnetic field around the  substance and thus magnetize it which convert it into a magnet. Thus electromagnet can be formed due to the magnetic effect of current.

Multiple choice physics magnetic effect of electric current oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

If we change in the direction of the current passing through the wire near to the magnetic needle:

  1. position of the pole of the needle will change

  2. position of the pole of the needle will remain same

  3. change in position of the pole depends on the current intensity

  4. none of the above is correct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When the direction of the current flowing through the wire is reversed, direction of the magnetic field, so produced, also changes its direction which results in changing the position of pole of needle kept near the wire.

Multiple choice physics magnetic effect of electric current oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

What did Oersted conclude from the experiment ?

  1. The current carrying wire must be acting as a magnet for the compass needle to deflect.

  2. The current carrying wire gets heated up and causes the compass needle to deflect.

  3. The current carrying wire sets up air currents that makes the compass needle to deflect.

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The deflection of the compass needle, whenever there is current in the wire show that a current carrying wire produces a magnetic field around it, which is essentially saying the current carrying wire must be acting as a magnet.

Multiple choice physics electromagnetic forces oersted experiment oersted's experiment magnetic field due to a straight current carrying conductor

With _____ in current in a wire near to magnetic needle, _____the vibration in the needle. Fill in the blank.

  1. increase, decreases

  2. increase, increases

  3. decrease, increases

  4. Non of above

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

More is the current in the wire near to the magnetic field, more is the strength of magnetic field generated around the wire and thus more is the vibration in the needle.