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 paramagnetic material classification of magnetic material magnetism

A bar magnet has been cut equally lengthwise and widthwise to give four equal pieces. The pole strength of each piece as compared to the pole strength of original bar magnet is :

  1. Same
  2. $\displaystyle \frac{1}{8}$
  3. $\displaystyle \frac{1}{4}$
  4. $\displaystyle \frac{1}{2}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When a bar magnet is cut equally lengthwise and widthwise into four equal pieces, each piece has 1/4 the length and 1/2 the width of the original. Pole strength is proportional to cross-sectional area (width × thickness). Original area A = w × t. Each piece has area = (w/2) × t = A/2. Therefore pole strength of each piece is half the original pole strength.

Multiple choice physics magnetism and matter paramagnetic material classification of magnetic material magnetism

Magnetic permeability of paramagnetic substances is?

  1. $0$
  2. $> 1$
  3. $< 1$
  4. $1$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Paramagnetic substances are substances which are weakly attracted by the magnetic field when they are placed in an external magnetic field. Magnetic permeability of paramagnetic substances is slightly greater than one whereas that of diamagnetic materials is slightly less than one.

Multiple choice physics magnetism and matter paramagnetic material classification of magnetic material magnetism

A paramagnetic substance when placed in an externally applied non-uniform magnetic field tends to ___________.

  1. increase the applied field

  2. decrease the applied field

  3. vary the applied field

  4. change the applied field
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Paramagnetic substances are the substances which are feebly attracted by a magnet. When a non-uniform external magnetic field is applied to a paramagnetic substance the magnetic field tries to aligned the magnetic moment in the direction of the field 

Completely alignment is however not possible, on account of thermal vibration. A better allingement can be achieved by increasing the strength of the applied magnetic field.

 

Multiple choice physics magnetism and matter paramagnetic material classification of magnetic material magnetism

When the atomic magnetic moments are randomly oriented in a solid its magnetic behavior is termed as

  1. semi-magnetic.

  2. anti-ferromagnetic.

  3. paramagnetic.

  4. poly crystalline.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When the atomic magnetic moments are randomly oriented in a solid its magnetic behavior is termed as paramagnetic.in paramagnetism electrons are unpaired.

Multiple choice physics magnetism and matter paramagnetic material classification of magnetic material magnetism

Liquid oxygen remains suspended between two pole forces of a magnet because it is:

  1. diamagnetic

  2. paramagnetic

  3. ferromagnetic

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

Oxygen is paramagnetic in nature. So if it will be attracted both by North pole or South pole. When it is placed exactly between two magnetic poles, the forces acting on it due to magnetic poles will be equal & opposite. Hence it will remain suspended between them.

Multiple choice physics magnetism and matter paramagnetic material classification of magnetic material magnetism

A substance is placed in a non uniform magnetic field. It experiences weak force towards the strong field. The substance is _________ type.

  1. Ferromagnetic

  2. Diamagnetic

  3. Paramagnetic

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

Paramagnetic substance has the property that when they are placed in an external magnetic field, they get weakly magnetised in the same direction as that of external magnetic field and are weakly attracted by the external magnetic field.
So, correct answer is option C.

Multiple choice physics magnetic effects of electric current magnetic field due to a circular current carrying conductor magnetic field produced in a circular loop oersted experiment field due to a current carrying conductor magnetic field due to a straight current carrying conductor magnetic field lines due to current

The magnetic lines of force due to straight current carrying conductor are:

  1. circular lines

  2. straight lines

  3. concentric lines

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

According to the right-hand thumb rule, the magnetic field lines around a long straight current-carrying conductor are concentric circles centered on the wire.

Multiple choice physics magnetic effects of electric current magnetic field due to a circular current carrying conductor magnetic field produced in a circular loop oersted experiment

What is the shape of a current-carrying conductor whose magnetic field pattern resembles that of a bar magnet?

  1. circular loop

  2. straight

  3. U-shaped

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

Answer is D.

A solenoid is an electromagnet. That is, it acts as a bar magnet only when electricity is passed through it. Its purpose is to generate a controlled magnetic field. 
A solenoid is a coil of insulated or enameled wire wound on a rod shaped form made of solid iron solid steel or powdered iron.

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

The strength and direction of the magnetic field depends on ..........

  1. Magnitude of electric current

  2. Direction of electric current

  3. Both A and B

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

In his experiment Oersted observed that the deflection of the needle compass changed according to the direction of the current and also as the current in the wire increased, the deflection of the needle increased. Thus he inferred that the strength and direction of the magnetic field depends on the magnitude and direction of current.