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 magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

The magnetic materials having negative magnetic susceptibility are

  1. non-magnetic

  2. para magnetic

  3. dia magnetic

  4. ferro magnetic
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Magnetic susceptibility is a dimensionless proportionality constant that indicates the degree of magnetisation of a material in response to an applied magnetic field.

Substances such as copper, iron have negative susceptibility as these substances are diamagnetic substances.
Substances with negative susceptibility signifies that they are repelled by magnets.

Multiple choice physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy. The work required to do this comes from.

  1. The lattice structure of the material of the rod

  2. The current source

  3. The induced electric field due to the changing magnetic field

  4. The magnetic field
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Here when electromagnet is connected to battery, emf source the magnetic field is produced which pushes rod upwards and so gravitational potential energy is stored.

This stored energy will require work which will come from current source or battery which is connected to electromagnet.
So option 2 is correct answer

Multiple choice physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

A paramagnet magnet behaves like a solenoid because both contain currents in the form of

  1. Circles

  2. Parabola

  3. Straight line

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

A paramagnet magnet behaves like a solenoid because both contain currents in the form of circle. The magnetic field is generated by the circular motion of the electron inside the atom.

Multiple choice physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

Domain formation is the necessary features of

  1. Diamagnetism

  2. Paramagnetism

  3. Ferromagnetism

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

Ferromagnetism materials exhibit a long range ordering phenomenon at the atomic level which causes the unpaired electron spins to line up parallel with each other in a region called domain. Within the domain, the magnetic field is intense, but in a bulk sample the material will usually be unmagnetised because the many domains will themselves be randomly oriented with respect to one another. Hence, domain formation is the necessary feature of ferromagnetic substance.

Multiple choice physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

If a solution of ferromagnetic material is poured into a U-tube and one arm of this is placed between the poles of a strong magnet with the meniscus in line with the field, then the level of the solution will:

  1. Rise

  2. Fall

  3. Rise till the liquid comes out

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

Ferromagnetic materials are strongly attracted to magnetic fields. When placed in a non-uniform magnetic field (like between the poles of a magnet), the liquid will be pulled toward the region of higher field strength, causing the level in that arm to rise.

Multiple choice physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

The value of magnetic susceptibility for para-magnetic substance is  

  1. infinity

  2. low positive

  3. low negative

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

Paramagnetic substance gets feebly magnetised in the direction of field and therefore, $I$ is very small and positive for paramagntic substances.
We know $X _m=I/H$
Therefore,$X _m$ is also very small and positive.

Multiple choice physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

Magnetism is a property present in ___________.

  1. Only a few materials

  2. Only ferromagnetic material

  3. Only paramagnetic material

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

Magnetization is present in all materials. It is a class of physical phenomenon that is mediated by Magnetic fields.

The magnetic state of different materials depends on temperature and other variables such as pressure and applied magnetic field.

 

Multiple choice physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

Needles $N _{1}, N _{2}$ and $N _{3}$ are made of a ferromagnetic, a paramagnetic and a diamagnetic substance respectively. A magnet when brought close to them will 

  1. attract all three of them.
  2. attract $\mathrm{N} _{1}$ and $\mathrm{N} _{2}$ strongly but repel $\mathrm{N} _{3}$.
  3. attract $\mathrm{N} _{1}$ strongly, $\mathrm{N} _{2}$ weakly and repel $\mathrm{N} _{3}$ weakly.
  4. attract $\mathrm{N} _{1}$ strongly, but repel $\mathrm{N} _{2}$ and $\mathrm{N} _{3}$ weakly.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ferromagnetic substances are strongly attracted by a magnet while, paramagnetic and diamaganetic substances are weakly attracted and repelled respectively.

Multiple choice chemistry phenomena around us comparison between physical and chemical changes introduction to physical and chemical changes change around us

In a certain change, colour and the magnetic properties of a substance changed. What reaction might this be?

  1. Chemical combination

  2. Photochemical reaction

  3. Irreversible reaction

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

Iron is magnetic at room temperature, but at 770 degrees Celsius iron loses its magnetism. However this change is temporary, hence it is an example of physical change.

and the change in color is a physical change because it is easily reversible without affecting the chemical nature of it.

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

Choose the correct answer from the alternatives given.
Maxwell in his famouse questions of  eletromagnetism introduce the concept of:

  1. ac current

  2. displacement current

  3. impedance

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

Maxwell in his famous question's of electromagnetism introduce the concept of displacement current

$J=J _E+J _C\ \quad=\epsilon _0\cfrac{dE}{dT}+\cfrac{dP}{dT}$

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

Which of the following has/have zero average value in a plane electromagnetic wave?

  1. Both magnetic and electric fields

  2. Electric fields only

  3. Magnetic field only

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

Both electric and magnetic field have sinusoidal nature in a plane electromagnetic wave. As we know, the average value of a sinusoidal wave is zero, so both magnetic and electric fields have average values zero.

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

Electro magnetic waves are transverse in nature as is evident by

  1. polarization

  2. interference

  3. reflection

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

Electromagnetic waves are transverse in nature as is evident by polarization interference and diffraction explain the wave nature of light or $EM$ waves polarization is the phenomenon by which we restrict the vibration of wave in a particular direction perpendicular to direction of $W$ are propagation. So, it explains the transverse nature of $EM$ waves.

Answer :- polarization.

Multiple choice the nature of electromagnetic waves space exploration and forms of light observing space: telescopes electromagnetic waves physics

On the basis of the following features identify correct option:
I. They require no material medium.
II. They are always transverse.
II. They are produced by accelerating charged particles

  1. Mechanical waves

  2. Electro-magnetic waves

  3. Both (1) and (2)

  4. Neither (1) and (2)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Electromagnetic waves do not need any material medium for their propagation and they are always transverse in nature e.g. light waves.