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 measurements and units kinds of units fundamental quantities standardized measurement

Which of the following pairs is not matched?

  1. Coefficient of self-induction : henry

  2. Magnetic flux : weber

  3. Electric flux : volt-meter

  4. Electric capacity : farad-meter
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Electric capacitance of a conductor is the ability with which the conductor can hold the charge.
In SI system, unit of capacitance is farad($F$).
Hence, option D is not matched.

Multiple choice physics magnetic effects of current and magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

When a bar magnet is suspended freely in a uniform magnetic field, identify the correct statements:

a) The magnet experiences only couple and undergoes only rotatory motion

b) The direction of torque is along the suspension wire

c) The magnitude of torque is maximum when the magnet is normal to the field direction

  1. only a and c are correct

  2. only a and b are correct

  3. only b and c are correct

  4. a, b, c are correct
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The bar magnet will only
experience a torque, It will not
experience any force
The direction of the torque will be
along the suspended wire according to
right hand thumbrule.
$\vec{z}=\vec{m}\times \vec{B}$
$=mB sin \theta .$
And its magnitude will be maximum if $\theta =90$


Multiple choice physics magnetic effects of current and magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

A magnetic needle is kept in a non uniform magnetic field. It experiences :

  1. a force and a torque

  2. a force but not a torque

  3. torque but not a force

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

Non uniform magnetic field gives rise to different forces at the different points on the needle thus producing a net force . This also gives rise to net torque

Multiple choice physics magnetic effects of current and magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

A bar magnet of magnetic moment $\overrightarrow{M}$, is placed in magnetic field of induction $\overrightarrow{B}$. The torque exerted on it is

  1. $\overrightarrow{ M }\cdot \overrightarrow{ B } $
  2. $-\overrightarrow{ M }\cdot \overrightarrow{ B } $
  3. $\overrightarrow{ M } \times \overrightarrow{ B } $
  4. $-\overrightarrow{ B } \times \overrightarrow{ M } $
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Torque is vector product of magnetic moment and the magnetic field.

Multiple choice physics magnetic effects of current and magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

If a bar magnet is kept perpendicular in a magnetic field of unit magnetic induction then its magnetic moment is equal to:

  1. magnetic flux

  2. torque

  3. pole strength

  4. magnetic flux density
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

From the given question, 

$B=1T$
$\theta=90^0$
The torque acting on the bar magnet is given by
$\tau=MBsin\theta=M\times 1\times sin90^0$
$\tau=M$
The magnetic moment is equal to the torque.
The correct option is B.

Multiple choice physics magnetic effects of current and magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

A magnet is kept fixed with its length parallel to the magnetic meridian. An identical magnet is parallel to this such that its center lies on perpendicular bisector of both. If the second magnet is free to move, it will have

  1. translatory motion only

  2. rotational motion only

  3. both translatory and rotational motion

  4. vibrational motion only
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Both translatory and rotational motion as it will exprrience both torque and force.

Multiple choice physics magnetic effects of current and magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

A current carrying wire is arranged at any angle in an uniform magnetic field, then

  1. only force acts on wire

  2. only torque acts on wire

  3. both

  4. none
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A current-carrying wire in a magnetic field experiences a Lorentz force given by F = I(L x B). Torque is only experienced if the wire is part of a loop or has a specific geometry allowing for a moment arm relative to an axis, but a simple wire experiences a net force.

Multiple choice physics magnetic effects of current and magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

A magnetic needle is kept in a non-uniform magnetic field. It experiences

  1. a force and a torque

  2. a force but not a torque

  3. a torque but not a force

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

A magnetic needle is a magnetic dipole.
In a non uniform Magnetic field Force on each of the poles will be different in both magnitude and direction.
Due to difference in Magnitude the dipole experiences a Force,
Due to difference in Direction the dipole experiences a Torque.

Multiple choice physics electric fields introduction to electrostatic force electric force charging and discharging

When we wear nylon dresses during winter then there is ______ current which gets produced due to contact with out body. Fill in the Blank.

  1. Magnetic

  2. Electrostatic

  3. Potential

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

When we wear nylon dresses during winter then there is electrostatic current which gets produced due to contact with out body.


Option B is correct.

Multiple choice physics turning effects of forces centre of gravity forces - vectors and moments acceleration due to gravity

A metallic rod falls under gravity with its ends pointing east and west. Then

  1. an emf is induced in it as it cuts the magnetic lines of force

  2. no emf is induced at all

  3. two emf of equal nut opposite signs are induced, giving no emf is

  4. its acceleration is equal to the product of g and the radius of the rod.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When rod falls due to earth magnetic field an emf is induced 

Hence,
option $A$ is correct answer.

Multiple choice uniform magnetic field lines of earth magnetism physics

In both $\tan A$ and $\tan B$ positions in a Deflection Magnetometer,  the bar magnet is always placed

  1. parallel to the magnetic needle of the deflection magnetometer

  2. parallel to the aluminum pointer of the deflection magnetometer

  3. perpendicular to the aluminum pointer

  4. parallel to the arm having the wooden scale
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In $\tan A$ position the bar magnet is placed horizontally, parallel to the arm of the deflection magnetometer and parallel to the magnetic needle of the deflection magnetometer. 

In $\tan B$ position the bar magnet is placed horizontally, perpendicular to the arm of the deflection magnetometer and parallel to the magnetic needle of the deflection magnetometer.