Magnet Questions

Collegedunia Team

Content Curator

A magnet is a material or object that produces a magnetic field as a result of its magnetic properties.

The magnetic field of a magnet may attract ferromagnetic objects (such as iron filings) and repel any other magnet.
Magnets suspended on a string always point in the north-south direction.
A magnet always has two magnetic poles that cannot be separated.
These are commonly referred to as the "North Pole" and "South Pole," respectively.
Similar poles repel each other, whereas opposites attract. Some materials naturally behave like magnets, whereas artificial magnets may be created.

Magnets are classified into the following types based on their source of magnetism:

Electromagnets: Electromagnets are powerful magnets made up of tightly wound wires surrounding an iron core. When a current passes through the wires, it acts like a magnet. The magnetic behavior disappears as soon as the current is turned off.
Permanent Magnets: Permanent magnets are made from "solid" magnetic force materials such as alloy and primary solid solution, which are subjected to a special process in an extremely strong force field throughout construction to align their crystalline internal structure, making magnets extremely difficult to remove. To remove the force field, a specified force field must be given, with the limit determined by the force of the force field.
Temporary Magnets: By subjecting ferromagnetic materials to a magnetic field, temporary magnets are created. When the magnetic field is removed, the materials lose their magnetic properties. These magnets are manufactured from a variety of soft materials. Iron and iron alloys, nails, and paper clips are some examples of temporary magnets.

Very Short Answers Questions [1 Mark Questions]

Ques. Electromagnet can be formed due to which of the following?

Chemical effect of electric current
Heating effect of electric current
Magnetic effect of electric current
None of the above

Ans. The correct answer is c. Magnetic effect of electric current

Explanation: Electromagnets are generated by passing an electric current through a wire wound around an iron core. The electric current creates a magnetic field around the substance, magnetizing it and converting it into a magnet. As a result of the magnetic effect of electricity, an electromagnet can be generated.

Ques. What is a magnet?

Ans. A magnet is a substance or object that generates a magnetic field. This magnetic field is invisible, but it is responsible for a magnet's unique property i.e. a force that attracts or repels other ferromagnetic elements such as iron, steel, nickel, cobalt, and so on.

Ques. What are the two poles of a magnet?

Ans. The two poles of a magnet are

North pole: The end of the magnet that points towards the geographic south of the earth when suspended freely is known as the North pole of the magnet.
South pole: The end of the magnet that points towards the geographic north of the earth when suspended freely is known as the South pole of the magnet.

Ques. What is a permanent magnet?

Ans. Permanent magnets are made from magnetized substances and have their own magnetic fields. A common example is a magnet used for sticking notes to metal objects.

Ques. What are ferromagnetic materials?

Ans. Ferromagnetic materials are a class of substances that exhibit significant magnetism in the direction of the field when a magnetic field is applied to them. Magnetism in these materials is caused mostly by the alignment patterns of its component atoms. These atoms behave like basic electromagnets.

Short Answers Questions [2 Marks Questions]

Ques. What is an electromagnet?

Ans. An electromagnet is a type of magnet that generates a magnetic field by using an electric current. Electromagnets are typically made of wire wound into a coil. A current flowing through the wire produces a magnetic field that concentrates in the coil's center hole.

Ques. What are temporary magnets?

Ans. Soft metals are used to make temporary magnets. When these materials are subjected to an electric current or a permanent magnet field, they exhibit magnetic characteristics. When they are removed from the magnetic field's range, they progressively lose their magnetic characteristics. Even in a small magnetic field, soft iron and certain iron alloys may be magnetized. When the magnetic field is removed, they quickly lose their magnetism. These excellent temporary magnets are utilized in electrical appliances such as electric motors and telephones.

Ques. Where do the oldest known descriptions of magnets come from?

Ans. The first known descriptions of magnets and their properties date approximately 2500 years ago in Anatolia, China, and India. Magnetic compasses were commonly used for navigation in Europe, China, the Arabian Peninsula, and others after the 12th century AD. By the start of the twentieth century, all identified elements and several compounds had been examined for magnetism.

Ques. What does the symbol B and H represent in magnetism?

Ans. The symbol B represents the magnetic flux density within a magnetized object. The symbol H represents the magnitude of a magnetic field or magnetizing force. The two values are expressed by the equation B = µH, where µ stands for the permeability of the material. It is a measure of the intensity of magnetization that may be induced by a given magnetic field.

Ques. What is meant by diamagnetism?

Ans. Diamagnetism is the property of materials that oppose a magnetic field; an applied magnetic field generates an induced magnetic field in them in the opposite direction, resulting in a repulsive force. Diamagnetism is a quantum mechanical phenomenon that occurs in all materials; it is called diamagnetic when it is the only contributor to magnetism.

Also Read:

Chapter Related Topic
Magnetic Properties	Ferromagnetism	Magnetic Field and Field Lines
Rare Earth Magnets	Permanent Magnets and Electromagnets	Magnetism and Matter

Long Answers Questions [3 Marks Questions]

Ques. What are the applications of diamagnetic materials?

Ans. The following are the applications of diamagnetic materials

Magnetic Levitation: Diamagnetic materials, such as superconductors, can exhibit strong repulsive forces when subjected to a magnetic field. Magnetic levitation trains and apparatus take advantage of the repulsion between magnets and superconductors to create frictionless journeys.
Magnetic Shielding: Magnetic fields can be effectively blocked by diamagnetic materials. Coatings or enclosures that redirect or dampen external magnetic fields can insulate sensitive electronics from interference.
Applications in Biology and Medicine: Diamagnetic materials have been used in magnetic resonance imaging (MRI) systems as well as other biological and medicinal applications. These materials are used to provide a consistent magnetic field and decrease distortions during imaging.

Ques. A compass needle, whose magnetic moment is 60 A m² pointing geographically North at a certain place, where the magnetic field is 40 µwb m^-2 experiences a torque of 1.2 x 10^-3 N m. Find the angle of torque.

Ans. Given

Torque experienced by the magnetic needle, τ = 1.2 x 10^-3 N m
The magnetic moment of the magnetic compass, m = 60 A m²
The strength of the magnetic field, B = 40 µwb m^-2 = 40 x 10^-6 wb m^-2

The torque experienced by a magnetic compass when placed in a uniform magnetic field, is given by

τ = mB sinθ

⇒ θ = sin^-1 (τ/mB)

On substituting the values, we get

⇒ θ = sin^-1 (1.2 x 10^-3 /60 x 40 x 10^-6 )

⇒ θ = sin^-1 0.5

⇒ θ = 30°

Ques. What are the applications of Ferromagnetic materials?

Ans. The following are the applications of Ferromagnetic materials

Electromagnets: Ferromagnetic materials, especially iron, are often used in the fabrication of electromagnets. These magnets are required for a variety of technologies, including MRI machines, electric motors, generators, and transformers.
Magnetic storage: Magnetic data storage devices that utilize ferromagnetic materials as main components include hard drives and magnetic tapes. Because of the magnetization-retaining feature, digital information may be kept and recovered even after an external field is withdrawn.
Magnetic sensors: Magnetic sensors constructed of ferromagnetic materials include Hall effect sensors and magnetic field sensors. These sensors are utilized in a variety of applications, including robotics, navigation systems, automotive systems, and non-destructive testing.

Very Long Answers Questions [5 Mark Questions]

Ques. What are the uses of magnets in everyday life?

Ans. The following are the uses of magnets in everyday life

Magnets are found in televisions, sound speakers, and radios. The electrical signal is converted to sound waves by a small coil of wire and a magnet inside a speaker.
Inside a generator, magnets are utilized to convert mechanical energy into electrical energy. Other types of motors, on the other hand, use magnets to convert electrical energy to mechanical energy.
The working of cranes can be performed with the use of electrically charged magnets while moving massive metal objects.
Magnets are used to extract metallic ores from broken rocks in filtering devices.
It is also used in the food processing industry to separate small metallic particles from grains, among other things.
Magnets are employed in MRI equipment to generate images of bone structure, organs, and tissues. Magnets are also utilized to treat cancer.
When we go on a walk, we frequently utilize a pocket compass to get directions. A magnetic needle on the pocket compass points north.
The dark strip on the back of debit and credit cards is magnetic and is used to store data, similar to hard drives in computers.

Ques. Calculate the permeability and susceptibility of a magnetic bar of cross-section 0.1 cm² having a magnetic flux of 2.41 x 10^-5 weber due to a magnetic intensity of 3200 A/m.

Ans. Given

Magnetic flux, Φ = 2.41 x 10^-5 weber
Magnetic intensity, H = 3200 A/m
Area of the cross-section of the magnet, A = 0.1 cm² = 0.1 x 10^-4 m²

The magnetic permeability of the magnetic bar is given by

µ = Strength of magnetic field (B)/Magnetic intensity (H)

⇒ µ = B/H …(i)

But, also we have

The Strength of the magnetic field, B = Magnetic flux (Φ)/Area of the cross-section of the magnet (A)

⇒ B = Φ/A

Hence, equation (i) becomes

µ = Φ/AH

On substituting the values, we get

µ = (2.41 x 10^-5 )/(0.1 x 10^-4 x 3200)

⇒ µ = 7.53 x 10^-4 T m A^-1

Now the relation between magnetic permeability and magnetic susceptibility is given by

µ = µ₀(1 + χ)

⇒ χ = (µ/µ₀) - 1

On substituting the values, we get

⇒ χ = (7.53 x 10^-4/4π x 10^-7) - 1

⇒ χ = 596.1

Ques. A bar magnet of magnetic dipole moment 1.5 J T^-1 is placed along the direction of a uniform magnetic field of 0.22 T. What is the amount of work done to turn the magnet with its magnetic moment

At 90° to the direction of the magnetic field
Opposite to the direction of the magnetic field

Ans. Given

Magnetic dipole moment of the bar magnet, m = 1.5 J T^-1
Strength of the magnetic field, B = 0.22 T

Work done by a bar magnet placed in a uniform magnetic field is given by

W = – mB (cosθ₂ – cosθ₁)

Where

m is the magnetic dipole moment of the magnet
B is the strength of the magnetic field
θ₂ is the final angle between the magnetic field and the magnetic dipole moment
θ₁ is the initial angle between the magnetic field and the magnetic dipole moment.

Initially, the magnetic dipole moment of the bar magnet is aligned with the direction of the magnetic field, therefore, θ₁ = 0°

Case (a): When the direction of the magnetic moment of the magnet is perpendicular to the direction of the magnetic field. Then work done by the magnetic dipole is given by

W = - (1.5 x 0.22) (cos 90° - cos0°)

⇒ W = - 0.33 (0 - 1) = 0.33 J

Case (b): When the direction of the magnetic moment of the magnet is opposite to the direction of the magnetic field. Then work done by the magnetic dipole is given by

W = - (1.5 x 0.22) (cos 180° - cos0°)

⇒ W = - 0.33 (-1 - 1) = 0.66 J

Previous Year Questions

Extraction of metal from the ore cassiterite involves...[JEE Advanced 2011]
Commonly used vectors for human genome sequencing are...[NEET UG 2014]
Interfascicular cambium and cork cambium are formed due to..
Pneumotaxic centre is present in...[UP CPMT 2007]
Reaction of HBr with propene in the presence of peroxide gives….[NEET UG 2004]
Assuming the expression for the pressure exerted by the gas on the walls of the container, it can be shown that pressure is...[MHT CET 2016]
Which among the following is the strongest acid?...[TS EAMCET 2017]
Isopropyl alcohol on oxidation forms..
A vector is not changed if..
Which of the following arrangements does not represent the correct order of the property stated against it?...[JEE Main 2013]

For Latest Updates on Upcoming Board Exams, Click Here: https://t.me/class_10_12_board_updates

Check-Out:

Class 11 & 12 PCMB Study Guides
NCERT Solutions for Class 12 Physics	Class 12 Physics Notes	Formulas in Physics
Topics for Comparison in Physics	Choice-based questions in physics	Topics in relation to physics
Physics Study Notes	Class 12 Physics Book PDF	Class 12 Physics Practicals
Important Derivations in Physics	SI units in Physics	Important Physics Constants and Units
Class 12 Physics Syllabus	Mendeleev's Periodic Table	NCERT Solutions for Class 12 Biology
NCERT Solutions for Class 12 English	NCERT Solutions for Class 11 Chemistry	Class 12 Chemistry Practicals
Class 12 Chemistry Notes	Important Chemical Reactions	Class 12 Maths Notes
Class 12 PCMB Notes	NCERT Class 12 Biology Book	NCERT Class 12 Maths Book
NCERT Class 12 Textbooks	NCERT Solutions for Class 11 Maths	NCERT Solutions for Class 11 Physics
NCERT Solutions for Class 12 Maths	NCERT Solutions for Class 11 Biology	NCERT Solutions for Class 11 English
NCERT Class 11 Chemistry Book	NCERT Class 11 Physics Book	NCERT Class 11 Biology Book
Class 11 Notes	Important Maths Formulas	Important Chemistry Formulas
Class 11 PCMB Syllabus	Chemistry Study Notes	Biology Study Notes
Periodic Table in Chemistry	Important Chemical Reactions	Comparison topics in Chemistry
Comparison Topics in Maths	Biology MCQs	Important Named Reactions
Maths MCQs	Comparison Topics in Biology	Chemistry MCQs