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

Curie temperature is the temperature above which 

  1. a ferromagnetic material becomes paramagnetic

  2. a paramagnetic material becomes diamagnetic

  3. a ferromagnetic material becomes diamagnetic

  4. a paramagnetic material becomes ferromagnetic.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Curie temperature is the temperature above which ferromagnetic materials lose their permanent magnetic field, the magnetism completely disappears. Above Curie temperature, the material behaves para-magnetically.

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

A ferromagnetic material is placed in an external magnetic field. The magnetic domains 

  1. Increase in size

  2. Decrease in size

  3. May increase or decrease is size

  4. Have no relation with the field
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When a ferromagnetic material is placed in an external magnetic field, the magnetic domains that are aligned with the field grow in size at the expense of those that are not, leading to magnetization.

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

The magnetic susceptibility is negative for

  1. Paramagnetic materials only

  2. Diamagnetic material only

  3. Ferromagnetic materials only

  4. paramagnetic and ferromagnetic materials
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Magnetic susceptibility is defined as the ratio of magnetization to the magnetic field intensity. For diamagnetic materials, the induced magnetization is in the opposite direction to the applied field, resulting in negative susceptibility.

Multiple choice physics friction advantages and disadvantages of friction merits and demerits of friction and methods to reduce it friction: a necessary evil

_______ helps in writing with a pen or pencil on a paper.

  1. Magnetic force

  2. Electric charge

  3. Chemical force

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

The irregularities between the paper and the pen or pencil create friction. Due to friction, the particles of ink or lead stick to the paper and get locked in its irregularities. If there would be no friction between the paper and pen or pencil, the ink/lead would not stick to the paper and we would not be able to write.

Multiple choice physics magnetic fields and electromagnetism magnetic flux density magnetic flux electromagnetic induction

When the normal to a coil points in the direction of magnetic field (B), then flux is 

  1. a scalar quantity

  2. a vector quantity

  3. neither scalar nor vector

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

Dot product of field and area vectors is flux . $\Phi=B.dS$, and we know dot product of two vectors is a scalar quantity.
Therefore, flux is scalar.

Multiple choice physics magnetic fields and electromagnetism magnetic flux density magnetic flux electromagnetic induction

State whether the following two statements are true or false
(i) Li has the same units as that of magnetic flux.
(ii) Li has the units volt-second and magnetic flux has the units coulomb-ohm.

  1. T T

  2. F F

  3. T F

  4. F T
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$\begin{array}{l} \left( 1 \right) This\, \, is\, \, True\, \, because\, \, \phi =Li \ \left( 2 \right) This\, \, is\, \, False\, \, because \ v=L\left( { \dfrac { { di } }{ { dt } }  } \right)  \ \Rightarrow L=\dfrac { v }{ q }  \ \Rightarrow Li=\dfrac { v }{ B }  \ Hence, \ option\, \, C\, \, is\, correct\, \, answer. \end{array}$

Multiple choice physics electrical conductivity of liquids does liquid conduct electricity? liquids conduct electricity do liquids conduct electricity?

When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection due to:

  1. electrical effect

  2. mechanical effect

  3. magnetic effect

  4. lighting effect
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection due to magnetic effect . This magnetic effect is produced by electric current, passing through it.

Multiple choice chemistry ionic equilibrium introduction to ionic equilibria in solution ionic equilibrium in solution ionisation of weak acids and weak bases

Diamagnetism is exhibited by_____

  1. cobalt

  2. water

  3. oxygen

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

Diamagnetic materials, like water, or water-based materials, have a relative magnetic permeability that is less than or equal to 1, and therefore a magnetic susceptibility less than or equal to 0. Diamagnetic materials are repelled by magnetic fields.

Multiple choice physics moving charges and magnetism field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

The magnetic field due to a current element is independent of :

  1. current through it

  2. distance from it

  3. its length

  4. nature of meterial
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$B=\dfrac{\mu _o}{4\pi}\dfrac{i\overrightarrow{dl}\times\overrightarrow{r}}{r^3}$

So it depends on all three : current , distance and length
but not on nature of material

Multiple choice physics moving charges and magnetism field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

The pattern of the magnetic field around a conductor due to an electric current flowing through it depends on

  1. amount of current flowing through the conductor

  2. amount of voltage supplied to the conductor

  3. size of conductor

  4. shape of the conductor
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
We know that;
$\vec B=\dfrac{\mu _0}{4\pi}\int { \dfrac { Idl\times {\vec  r  } }{ \left| { r }^{ 1 } \right| ^{ 3 } }  } $
Where, $\vec B$ is magnetic field, $\vec I$ is current.
Thus magnitude of $\vec B$ depend on I, but pattern of magnetic field depend on shape of conductor as the direction of magnetic field is obtained used Cut finger rule i.e, pointing right hand thumb in current direction, Curl fingers describes direction thus pattern.