MCQs

How is the difference between ferromagnetic, paramagnetic, and diamagnetic materials clarified?
A) Their colour B) Their density C) The domain theory of magnetism and the effects of external magnetic fields on these materials D) Their hardness

What are the most powerful permanent magnets in the world made from?
A) Iron and Boron alloy (NdFeB) B) Steel and nickel C) Cobalt and copper D) Only from natural magnetite

What are the magnetic properties of an electromagnet like?
A) Permanent B) Temporary C) Unchanging D) Very low

In which of the following devices are permanent magnets commonly used?
A) Circuit breaker B) Loudspeaker C) Electric crane D) Magnetic recording

What is done to push the maglev train forward?
A) It is manually pushed B) Pushing magnets are installed along the guideway and on both sides of the train C) It is pushed only by air pressure D) It is run by an engine

Permanent magnets cannot be made by which of the following materials?
A) Steel B) Neodymium C) Soft iron D) Alnico

More than a thousand years ago, for what purpose did the Greeks use lodestone?
A) For land and sea navigation B) For construction C) For agriculture D) For food storage

What is the purpose of a circuit breaker?
A) To continuously increase current B) To safely allow current above a certain limit to pass C) To turn off the circuit switch when the current exceeds a certain limit D) To stop the flow of electricity

What are examples of magnetic materials?
A) Iron, nickel, cobalt B) Copper wire, glass bottle, rubber C) Wooden toy, plastic comb D) Brass, copper, glass

For what purpose are permanent magnets used in the medical field?
A) To purify blood B) To remove iron particles from eyes C) To join bones D) To measure heartbeat

What does the N-pole of a compass needle indicate?
A) The strength of the magnetic field B) The numerical value of the magnetic field C) The direction of the magnetic field D) The size of the magnet

When a lodestone was freely suspended, in which direction did it stop?
A) East-West B) North-South C) Up-Down D) Left-Right

Electromagnets are an example of what type of magnets?
A) Permanent magnets B) Natural magnets C) Temporary magnets D) Diamagnetic magnets

Which of the following is a common method to magnetize a material?
A) Hitting B) Heating C) Stroking D) Placing inside a solenoid with A.C. current

What is the definition of a magnetic field?
A) A region where a magnetic pole experiences a force B) The material that attracts a magnet C) The process of identifying the poles of a magnet D) Heat generated by a magnet

Which material is best suited to protect a device from an external magnetic field?
A) Wood B) Plastic C) Steel D) Soft iron

What is an essential part of electric motors and generators?
A) Temporary magnets B) Electromagnets C) Permanent magnets D) Natural magnets

When the voice coil and the cone attached to it vibrate back and forth, what is produced?
A) Light B) Heat C) Sound D) Electricity

What does magnetization refer to?
A) Conversion of magnetic material into a magnet B) A magnet losing its properties C) Two magnets repelling each other D) Weakening of the magnetic field

When two freely suspended bar magnets are brought close to each other, what do their opposite poles do?
A) Repel each other B) Show no reaction C) Show a slight reaction D) Attract each other

Why is it necessary to analyse the use of magnets in recording technology and to protect electronic devices from strong magnetic fields?
A) Because magnets get hot B) Because strong magnetic fields can corrupt data C) Because magnets are very heavy D) Because magnets are expensive

How can a material be magnetized and demagnetized (in terms of domain theory)?
A) Only by heating B) Stroking method, heating, aligning in north-south direction and striking, using a solenoid C) Only by passing electric current D) Only by cooling

What do flour mills use permanent magnets for?
A) To grind grain B) To measure the density of grain C) To remove iron nails etc. from grain before grinding D) To store grain

What are the uses of permanent magnets and electromagnets?
A) Recording technology B) Medical equipment C) Electric motors and generators D) All of these

What was the characteristic of the stone discovered by ancient Greeks, called lodestone or magnetite?
A) It attracted gold B) It attracted iron objects C) It produced light D) It purified water

How can magnetic lines of force around a bar magnet be drawn?
A) With a ruler B) With a small compass C) With a magnetic pencil D) By hand

In an electric generator, when a coil is rotated between the poles of a permanent magnet, what is produced?
A) Heat B) Light C) EMF D) Sound

In a maglev train, what is done with the help of magnets?
A) It is lifted a few centimetres above the guideway (track) B) It is run on the track C) It is pushed D) It is stopped

Where do magnetic field lines start and end?
A) Start from the S-pole and end at the N-pole B) Start from the N-pole and end at the S-pole C) Can start from any pole and end at any pole D) Start from poles and end in the air

What is a magnetic field?
A) The weight of a magnet B) The region around a magnet where another magnetic object experiences a force C) The inner part of a magnet D) The density of magnetic material

When do temporary magnets lose their magnetic properties?
A) When they are heated B) When the magnetic field is removed C) When they are cooled D) When they are broken

What determines the direction of a magnetic field at a given point?
A) The direction of the force on the S-pole of a magnet at that point B) The direction of the force on the N-pole of a magnet at that point C) The distance between magnetic field lines D) The strength of the magnet

Which material is commonly used to make temporary magnets?
A) Steel B) Soft iron C) Copper D) Aluminium

What is the maglev train called in Japan?
A) Bullet Train B) Speed Train C) Air Train D) Rocket Train

What happens by varying the strength of the electromagnet in a telephone receiver?
A) Light is produced B) Sound is produced C) Heat is produced D) No difference

What type of switch is a magnetic relay?
A) Which operates manually B) Which operates by heat C) Which operates through an electromagnet D) Which operates by light

The magnetic field will be stronger where what happens?
A) The field lines are far from each other B) The field lines are relatively closer to each other C) The field lines are straight D) The field lines are curved

If a bar magnet is suspended horizontally by a string and allowed to come to rest, in which direction will it stop?
A) East-West B) North-South C) Up-Down D) Left-Right

What indicates the relative strength of a magnetic field?
A) The size of the magnetic poles B) The length of the magnetic field lines C) The distance between magnetic field lines D) The weight of the magnet

Which magnets are used in moving-coil loudspeakers?
A) Temporary magnets B) Electromagnets C) Permanent magnets D) Diamagnetic magnets

What does alternating current (AC) passing through the voice coil in a moving-coil loudspeaker produce?
A) Heat B) Light C) Variable force D) Magnetic noise

Which materials are found naturally, while powerful magnets are artificially made from nickel, cobalt, steel and certain other alloys?
A) Temporary magnets B) Electromagnets C) Permanent magnets D) Non-magnetic materials

For how long does an electromagnet remain a magnet?
A) As long as it is heated B) As long as electric current passes through the coil C) As long as it is cooled D) As long as it is broken

If a magnet is broken into thousands of pieces, what happens?
A) It loses its magnetic properties B) Each piece will be a complete magnet with its North and South poles C) Only the largest piece will remain a magnet D) Only the central piece will remain a magnet

What terms are involved in describing forces between magnetic poles and magnets?
A) Attraction and repulsion B) Magnetism and non-magnetic materials C) North Pole (N) and South Pole (S) D) All of these

In what form are magnets fitted in the doors of refrigerators and freezers?
A) In the form of wires B) In the form of magnetic strips C) In the form of round beads D) In powder form

If we break a bar magnet into two equal pieces, will we get separate North and South poles?
A) Yes, always B) No, each piece will have its own two poles C) Only if the pieces are very small D) It depends on the shape of the pieces

What is the accurate test for an object to be a magnet?
A) Attracting it B) Like poles repelling each other C) Cooling it D) Heating it

An electric motor is the reverse operation of what?
A) Electric heater B) Electric generator C) Electric bulb D) Electric fan

The strength of the magnetic field at a point is proportional to what?
A) The number of lines passing through a unit area drawn parallel to the magnetic lines of force there B) The number of lines passing through a unit area placed perpendicular to the magnetic lines of force there C) The size of the magnet D) The volume of the magnetic material

What is true about magnetic lines of force?
A) They are always straight lines B) They cross one another C) They enter the north pole D) They enter the south pole

What are examples of non-magnetic materials?
A) Brass, copper, wood, glass, plastic B) Iron, nickel C) Cobalt, steel D) Paper clips, iron nails

How can a magnetic field pattern be observed?
A) By heating the magnet B) By immersing the magnet in water C) By placing the magnet in light D) By sprinkling iron filings on a glass plate over the magnet

What was the basis for the invention due to the unique property of lodestone?
A) Electrical devices B) Making a compass C) Water filter D) Making spectacles

What is the end of the magnet that faces north called?
A) South Magnetic Pole (S) B) North Magnetic Pole (N) C) Neutral Pole D) Zero Pole

What does induced magnetism refer to?
A) When a magnet loses its properties B) When a magnetic material is magnetized C) When two magnets repel each other D) When the magnetic field disappears

Which one of the following is not a magnetic material?
A) Aluminium B) Cobalt C) Iron D) Nickel

When two freely suspended bar magnets are brought close to each other, what do their like poles do?
A) Attract each other B) Show no reaction C) Show a slight reaction D) Repel (push away) each other

How can the strength of an electromagnet be increased?
A) By decreasing the number of cells in the battery B) By decreasing the number of turns in the coil C) By increasing the number of cells in the battery or increasing the number of turns in the coil D) Only by increasing the length of the wire

How can soft magnetic material (like soft iron) be used to provide shielding from magnetic fields?
A) By heating it B) By cooling it C) By using it as a barrier that allows the magnetic field to pass through it D) By passing electric current through it

What is the difference between temporary and permanent magnets?
A) Temporary magnets always retain their properties B) Permanent magnets lose properties when the magnetic field disappears C) Temporary magnets work in the presence of a magnetic field D) Permanent magnets only occur naturally

What do magnetic lines of force show?
A) The colour of the magnet B) The hardness of the magnet C) The weight of the magnet D) The paths of particles in a magnetic field

Short Questions

(i) How are electromagnets made, and what are their properties?
(ii) What are the most powerful permanent magnets made from?
(iii) Explain the uses of permanent magnets and electromagnets.
(iv) Define a magnetic field and how it can be demonstrated experimentally.
(v) Differentiate between paramagnetic and diamagnetic materials.
(vi) Analyse the use of magnets in recording technology and explain why electronic devices need to be protected from strong magnetic fields.
(vii) A steel bar has to be magnetized by placing it inside a solenoid such that end A of the bar becomes the N-pole and end B becomes the S-pole. Draw the circuit diagram of the solenoid showing the steel bar inside it.
(viii) Is an isolated magnetic pole possible? Explain.
(ix) What is the purpose of a circuit breaker, and how does it work?
(x) Describe the method of identifying if an object is a magnet.
(xi) Four similar solenoids are placed in a circle. The magnitude of current in all of them should be the same. Show by diagram the direction of current in each solenoid such that when current in any one solenoid is switched OFF, the net magnetic field at the centre O is directed towards that solenoid. Explain your answer.
(xii) Explain induced magnetism.
(xiii) Electric current or motion of electrons produces a magnetic field. Is the reverse process true, that is, does the magnetic field give rise to electric current? If yes, give an example and describe it briefly.
(xiv) Explain that the direction of a magnetic field at a point is the direction of the force on the N-pole of a magnet at that point.
(xv) What is the difference between temporary and permanent magnets? Clarify with examples.
(xvi) What are magnetic lines of force?
(xvii) What is the amazing use of electromagnets in a maglev train?
(xviii) What are magnetic domains?
(xix) What is magnetization, and how can it be achieved?
(xx) Which type of magnetic field is formed by a current-carrying long coil?
(xxi) Differentiate between temporary and permanent magnets.
(xxii) What is the difference between magnetic and non-magnetic materials? Clarify with examples.
(xxiii) Explain that the relative strength of a magnetic field is indicated by the distance between magnetic field lines.
(xxiv) State the principles of attraction and repulsion of magnetic poles.
(xxv) How is the strength of a magnetic field at a point indicated?
(xxvi) Define the magnetic field of a magnet.
(xxvii) How do permanent magnets help produce sound in a moving-coil loudspeaker?
(xxviii) Define a magnetic field.
(xxix) Name some uses of permanent magnets and electromagnets.
(xxx) What is the pattern of the magnetic field of a horseshoe magnet like?
(xxxi) What are temporary and permanent magnets?
(xxxii) Explain how soft magnetic material can be used to provide shielding from magnetic fields.
(xxxiii) What is the role of permanent magnets in an electric generator?
(xxxiv) What did the Greeks discover about a stone called lodestone or magnetite, and what was its characteristic?
(xxxv) Differentiate between ferromagnetic, paramagnetic and diamagnetic materials.
(xxxvi) In which direction did lodestone stop when freely suspended, and what invention was based on this property?
(xxxvii) By what factors can the strength of an electromagnet be increased?
(xxxviii) How does a magnetic relay work?
(xxxix) Explain how a material can be magnetized and demagnetized in terms of the domain theory of magnetism.
(xl) Describe the process of pushing a maglev train forward.
(xli) What is the function of an electromagnet in a telephone receiver?
(xlii) Explain the forces between magnetic poles, magnets and magnetic materials.
(xliii) What is a Neutral Point?
(xliv) State any five uses of permanent magnets.
(xlv) What are magnetic lines of force, and how can they be drawn?

Long Questions

What is a circuit breaker? Describe its working with the help of a diagram.

If the strength of a magnetic field at a point is 0.01 T, and the number of field lines per unit area is doubled, what will be the new field strength?

Describe the strength of a magnetic field in terms of magnetic lines of force. Explain it by drawing a few diagrams for the fields as examples.

Explain the properties of magnets with diagrams.

Why are ferromagnetic materials suitable for making magnets?

A coil of wire has 300 turns and carries a current of 3 A. If the length of the solenoid is 25 cm, calculate the strength of the magnetic field.

Differentiate between paramagnetic, diamagnetic and ferromagnetic materials with reference to the domain theory.

Explain the role of magnets in recording technology (magnetic tapes, hard disks, etc.).

How can you identify whether an object is a magnet or a magnetic material?

What is soft iron shielding, and why is it used in sensitive instruments?

How can a steel bar be magnetized using the stroking method and solenoid method?

A bar magnet creates a magnetic field strength of 0.002 T at a distance of 5 cm from its pole. What will be the field strength at 10 cm?

Describe the structure and working of an electromagnet with a labelled diagram.

How can you identify whether an object is a magnet or a magnetic material?

Describe the working of an electric bell using an electromagnet.

Differentiate between temporary and permanent magnets with examples.

Explain the domain theory of magnetism in detail.

Describe the concept of induced magnetism with examples.

Describe the strength of a magnetic field in terms of magnetic lines of force. Explain it by drawing a few diagrams for the fields as examples.

A solenoid has 500 turns, and a current of 2 A flows through it. Calculate the magnetic field produced at the centre of the solenoid if its length is 20 cm.

Differentiate between paramagnetic, diamagnetic and ferromagnetic materials with reference to the domain theory.

A magnet attracts only a magnet. Explain the statement.

What is a circuit breaker? Describe its working with the help of a diagram.

A magnet attracts only a magnet. Explain the statement.

A hard disk operates at a speed of 7200 rpm. How many complete rotations does it make in 10 seconds?

Why are ferromagnetic materials suitable for making magnets?

A Maglev train uses an electromagnet to produce a lifting force of 4000 N. If the current is increased by 50%, what will be the new force?