816 + Interview Questions in MAGNETISM IN GENERAL AWARENESS Page 15 InterviewSolution

701.	Assertion: Electromagnets are made of soft iron. Reason: Coercivity of soft iron is small.A. If both assertion and reason are true and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. f assertion is true but reason is false.D. If the assertion and r eason both are false
Answer» Correct Answer - A

Discussion

702.	Interstellar space has an extremely weak magnetic field of the order of 1012T. Can such a weak field be of any significant consequence? Explain.
Answer» A weak field of the order of 10^-12 T can cause the charged particles to move along circular paths of very large radii. Over a small distance, we may not be able to notice the deflection in the path of the charged particles but over large interstellar distance, the distance is quite noticeable.

Discussion

703.	A magnetic needle of dipole moment `0.067 JT^(-1)` oscillates with a period of 2/3 s in a uniform magnetic field of 100 G . Find the moment of inertia of the needle about the axis of oscillations.
Answer» Correct Answer - `0.75 xx 10^(-5) kg m^(2)`

Discussion

704.	The magnetic field near the centre of a current carrying coil is uniform and ________A. parallel to the plane of coil.B. perpendicular to the plane of coilC. circularD. both (b) and (c)
Answer» Correct Answer - B

Discussion

705.	Ratio between total intensity of magnetic field at equator to poles isA. `1:1`B. `1:2`C. `2:1`D. `1:4`
Answer» Correct Answer - A

Discussion

706.	The lines joining the places of the same horizontal intensity are known asA. Isogonic linesB. Aclinic linesC. Isoclinic linesD. Isodynamic lines
Answer» Correct Answer - D

Discussion

707.	The angle which are total magnetic field of earth makes with the surface of the earth is calledA. declinationB. magnetic meridianC. geographic meridianD. inclination
Answer» Correct Answer - D The angle which the total magnetic field of earth makes with the surface of the earth is called inclination.

Discussion

708.	For soft iron, in comparison with steelA. hysteresis loss is moreB. hysterisis loss is sameC. hysteresis loss is lessD. hysterisis loss is negligible
Answer» Correct Answer - C

Discussion

709.	Aclinic lines are the lines joining places ofA. zero dipB. equal dipC. zero declinationD. equal declination
Answer» Correct Answer - A Aclinic lines are the lines joining places of zero dip .

Discussion

710.	`chi_(1)` and `chi_(2)` are susceptinilities of diamagnetic substance at temperatures `T_(1)K` and `T_(2)K` respectively. ThenA. `chi_(1)T_(1)=chi_(2)T_(2)`B. `chi_(1)=chi_(2)`C. `chi_(1)sqrt(T_(1))=chi_(2)sqrt(T_(2))`D. `chi_(1)T_(2)=chi_(2)T_(1)`
Answer» Correct Answer - B

Discussion

711.	Define following terms in case of magnetic maps:i. Isomagnetic charts ii. Isodynamic lines iii. Isogonic lines iv. Aclinic lines
Answer» i. Isomagnetic charts: Magnetic maps drawn by joining places with the same value of a particular element are called isomagnetic charts. ii. Isodynamic lines: Lines joining the places of equal horizontal components (B ) on magnetic maps are known as isodynamic lines. iii. Isogonic lines: Lines joining the places of equal declination (α) on magnetic maps are called isogonic lines. iv. A clinic lines: Lines joining the places of equal inclination or dip (ø) on magnetic maps are called a clinic lines.

711.

Define following terms in case of magnetic maps:i. Isomagnetic charts ii. Isodynamic lines iii. Isogonic lines iv. Aclinic lines

Answer»

i. Isomagnetic charts: Magnetic maps drawn by joining places with the same value of a particular element are called isomagnetic charts.

ii. Isodynamic lines: Lines joining the places of equal horizontal components (B ) on magnetic maps are known as isodynamic lines.

iii. Isogonic lines: Lines joining the places of equal declination (α) on magnetic maps are called isogonic lines.

iv. A clinic lines: Lines joining the places of equal inclination or dip (ø) on magnetic maps are called a clinic lines.

Discussion

712.	In a permamnent magnet at room temperatureA. magnetic moment of each molecules is zeroB. the individual molecules have non-zero magnetic moments which are all perfectly alignedC. domains are partially alignedD. domains are all perfectly aligned
Answer» Correct Answer - C

Discussion

713.	Magnetic equator and geographical equator of the earth are same. Is this true or false?
Answer» False. Magnetic equator and geographical equator of the earth are not same. By definition, they are different. Magnetic declination is the angle between magnetic equator and geographical equator of the earth.

713.

Magnetic equator and geographical equator of the earth are same. Is this true or false?

Answer»

False.

Magnetic equator and geographical equator of the earth are not same. By definition, they are different. Magnetic declination is the angle between magnetic equator and geographical equator of the earth.

Discussion

714.	Which of the following is an artificial magnet ?A. bar magnetB. Horse-shoe magnetC. magnetic needleD. all the above
Answer» Correct Answer - D

Discussion

715.	A conducting wire can give magnetic pole when it is _________A. bent into the form of a circular ringB. placed in an external magnetic fieldC. suspended freely in airD. All the above
Answer» Correct Answer - A

Discussion

716.	The strength of a magnetic field increases as _________A. the number of magnetic lines of force passing through a given area increasesB. strength of the magnetic poles increasesC. distance between the magnetic poles increasesD. does not exist
Answer» Correct Answer - D

Discussion

717.	A point near the equator hasA. `B_(V)gtgtB_(H)`B. `B_(H)gtgtB_(V)`C. `B_(V)=B_(H)`D. `B_(V)=B_(H)=0`
Answer» Correct Answer - B

Discussion

718.	Which of the following is a property shown by a magnet ?A. Attractive propertyB. Directive propertyC. IndcutionD. All the above
Answer» Correct Answer - D

Discussion

719.	Two bar magnets are kept so that each magnet is in contact with another magnet as shown in the figure below. In which of the arrangements do the magnets lose magnetism faster ? Why ?
Answer» In which among them does the molecular magnet rearange randomly faster ? How is the alignment of the molecular magnetis related with the direction of the external applied magnetic field applied ?

Discussion

720.	The magnetic field due to a bar magnet _____A. has the same direction at any pointB. is uniformC. is non-uniformD. does not exist
Answer» Correct Answer - C

Discussion

721.	A line joining places of zero declination is calledA. agonicB. isoclinicC. isodynamicD. isogonal
Answer» Correct Answer - A

Discussion

722.	A freely suspended magnet lies in the horizontal plane at ___________of earth.
Answer» Correct Answer - magnetic equator

Discussion

723.	Three identical thin bar magnets each of moment `M` are placed along three adjacent sides of a regular hexagon as shown in figure. The resultant magnetic moment of the system is A. `M`B. `Msqrt3`C. `Msqrt2`D. `2M`
Answer» Correct Answer - D `bar(M)_(net)=bar(M)_(1)+bar(M)_(2)+bar(M)_(3)`

Discussion

724.	The resultant magnetic moment for the following arrangement is A. `M`B. `2M`C. `3M`D. `4M`
Answer» Correct Answer - B `M_(R )=sqrt(M_(1)^(2)+M_(2)^(2)+2M_(1)M_(2)costheta)`

Discussion

725.	The resultant magnetic moment for the following arrangement (non coplanar vectors) A. `M`B. `2M`C. `3M`D. `4M`
Answer» Correct Answer - B `M_(res)=sqrt((sqrt3M)^(2)+M^(2))`

Discussion

726.	The point at which the resultant magnetic effect is zero is called _______
Answer» Correct Answer - neutral point

Discussion

727.	Resultant force acting on a diamagentic material in a magnetic field is in directionA. from stronger to the weaker part of the magnetic fieldB. from weaker to the strogner part of the magnetic fieldC. perpendicular to the magnetic fieldD. in the direction making `60^(@)` to the magnetic field
Answer» Correct Answer - A Resultant force acting on a diamagnetic material in a magnetic field is in direction from stronger to the weaker part of the magnetic field.

Discussion

728.	Assertion: Above Curie temperature, a frerromagnetic material becomes paramagnetic. Reason: When a magnetic material is heated to very high temperature, it loses its magnetic properties.A. a ferromagnetic substance becomes paramagneticB. a paramagnetic substance becomes diamagneticC. a diamagnetic substance becomes paramagneticD. a paramagnetic substance becomes ferromagnetic
Answer» Correct Answer - A

Discussion

729.	A magnetic needle lying parallel to a magnetic field requires `W units` of work to turn it through `60^(@)`. The torque needed to maintain the needle in this position will beA. `sqrt(3)W`B. WC. `(sqrt(3))/(2)W`D. 2W
Answer» Correct Answer - A

Discussion

730.	If a magnet is hanged with its magnetic axis then it stops inA. Magnetic meridianB. Geometric meridianC. Angle of dipD. None of these
Answer» Correct Answer - A

Discussion

731.	The magnetic lines of force inside a bar magnet:(A) Are from north-pole to south-pole of the magnet(B) Do not exist(C) Depend upon the area of cross-section of bar magnet(D) Are from south-pole to north-pole of magnet
Answer» The answer is (D) Are from south-pole to north-pole of magnet

Discussion

732.	Magnetic lines of force due to a bar magnet do not intersect becauseA. a point always has a single net magnetic fieldB. the lines have similar charges and so repel each otherC. the lines always diverge from a single pointD. None of the above
Answer» Correct Answer - D Magnetic lines of force due to a bar magnet do not intersect becaues if they intersect then it means, there are two directions of magnetic field intensity which is impossible.

Discussion

733.	the magnetic lines of force inside a bar magnetA. Are from south-pole to north-pole of the magnetB. Are from north-pole to south-pole of the magnetC. Do not existD. Depend upon the area of cross-section of the bar magnet
Answer» Correct Answer - A

Discussion

734.	Magnetic lines of force due to a bar magnet do not intersect becauseA. A point always has a single net magnetic fieldB. The lines have similar charges and so repel each otherC. The lines always diverge from a single pointD. The lines need magnetic lenses to be made to intersect
Answer» Correct Answer - A

Discussion

735.	The magnet field lines due to a bar magnet are correctly shown inA. Intersect at the neutral pointB. Intersect near the poles of the magnetC. Intersect on the equatorial axis of the magnetD. Do not intersect at all
Answer» Correct Answer - D

Discussion

736.	Two lines of force due to a bar magnetA. intersect at the neutral pointB. intersect near the poles of the magnetC. intersect on the equatorial axis of the magnetD. do not intersect at all
Answer» Correct Answer - D Two lines of forces due to a bar magnet do not intersect at all.

Discussion

737.	Torques `tau_(1)` and `tau_(2)` are required for a magnetic needle to remain perpendicular to the magnetic fields at two different places. The magnetic field at those places are B1 and B2 respectively, then `(B_(1))/(B_(2))` isA. `(tau_(2))/(tau_(1))`B. `(tau_(1))/(tau_(2))`C. `(tau_1+ tau_2)/(tau_1 - tau_2)`D. `(tau_1- tau_2)/(tau_1 + tau_2)`
Answer» Correct Answer - B Torque , ` tau=MB sin theta ` `tau_(1)=MB_(1) sin 90^(@)=MB_(1)` ` tau=(2)=MB_(2) sin 90^(@)=MB_(2)` ` or (MB_(1))/(MB_(2))=(tau_(1))/(tau_(2))` `:. (B_(1))/(B_(2))=(tau_1)/(tau_2)`

Discussion

738.	A toroid of n turns, mean radius R and cross-sectional radius a carries current I. It is placed on a horizontal table taken as x-y plane. Its magnetic moment `vecM`A. is non-zero and points in the Z-direction by symmetryB. points along the axis of the toroid `(m=m phi)`C. is zero, otherwise there would be a field falling as ` (1)/(r^(3))`D. is pointing radially outwards
Answer» Correct Answer - C In case of toroid , the magnetic field is only confined inside the body of toroid in the form of concentric magnetic lines of force and there is no magnetic field outside the body of toroid. This is because the loop encloses no current . Thus , the magnetic moment of toroid is zero . In general , if we take r as a large distance outside the toroid , then `m prop (1)/(r^(3))` . But this case is not possible here .

Discussion

739.	The magnetic susceptibility of a rod is `499`. The absolute permeability of vacuum is `4pixx10^(-7)H//m`. The absolute permeability of the material of the rod isA. `pixx10^(-4)H//m`B. `2pixx10^(-4)H//m`C. `3pixx10^(-4)H//m`D. `4pixx10^(-4)H//m`
Answer» Correct Answer - B `mu=mu_(@)[1+chi]`

Discussion

740.	The period of a thin magnet in a magnetic field is `2s`. It is cut into four equal parts by cutting it along length and breadth. The period of each of them in the same field isA. `1 s`B. `2 s`C. `3 s`D. `4 s`
Answer» Correct Answer - B `T=2pisqrt((I)/(MB_(H)))` and `T alpha sqrt((I)/(M))`

Discussion

741.	Define magnetic flux.
Answer» The number of magnetic field lines crossing per unit area is called magnetic flux B. Φ_B = \(\vec B . \vec A\)= BA cos θ = B ⊥ A

Discussion

742.	When a charged particle enters a uniform magnetic field its kinetic energy-(a) remains constant (b) increases (c) decreases (d) becomes zero
Answer» (a) remains constant

Discussion

743.	Define magnetic flux density.
Answer» The magnetic flux density is defined as the number of magnetic field lines crossing unit area kept normal to the direction of line of force. Its unit is Wb m^-2 or tesla.

Discussion

744.	The unit of magnetic flux density is ………
Answer» The unit of magnetic flux density is Weber metre² (or) tesla.

Discussion

745.	Aproton enters a magnetic field of flux density 1.5 Wb/m2 with a speed of 2x 107 m/s at angle of 30° with the field. The force on the proton will be-(a) 0.24 x 10-12 N (b) 2.4 x 10-12 N (c) 24 x 10-12 N (d) 0.024 x 10-12 N
Answer» (b) 2.4 x 10^-12 N F = Bqv sin θ =1.5 x 1.6 x 10^-19x 2 x 10⁷x sin 30° = 2.4 x 10^-12N

745.

Aproton enters a magnetic field of flux density 1.5 Wb/m2 with a speed of 2x 107 m/s at angle of 30° with the field. The force on the proton will be-(a) 0.24 x 10-12 N (b) 2.4 x 10-12 N (c) 24 x 10-12 N (d) 0.024 x 10-12 N

Answer»

(b) 2.4 x 10^-12 N

F = Bqv sin θ =1.5 x 1.6 x 10^-19x 2 x 10⁷x sin 30°

= 2.4 x 10^-12N

Discussion

746.	What are natural magnets?
Answer» Natural magnets exists in the nature and can be found in rocks and sandy deposits in various parts of the world.

Discussion

747.	How can the speed of rotation of a coil be increased? Write at least three methods.
Answer» The speed of rotation of a coil can be increased by; increasing the strength of the Current in the coil increasing the area of the coil increasing the strength of the magnetic field.

747.

How can the speed of rotation of a coil be increased? Write at least three methods.

Answer»

The speed of rotation of a coil can be increased by;

increasing the strength of the Current in the coil
increasing the area of the coil
increasing the strength of the magnetic field.

Discussion

748.	Name some equipmetns that use electromagnetism for functioning.
Answer» Many of the medical equipments such as scanners, x-ray equipments and other equipments also use principle of electromagnetism for their functioning.

Discussion

749.	Explain why the ozone layer is not affected by the Solar wind.
Answer» Magnetic field can penetrate through all kinds of materials. The Earth produces its own magnetic field, which shields the earht’s ozone layer from the solar wind.

Discussion

750.	A current carrying conductor of certain length, kept perpendicular to the magnetic field experiences a force F. What will be the force if the current is increased four times, length is halved and magnetic field is tripled?
Answer» F = ILB = (4I) × ( L / 2) × (3 B) = 6 F Therefore, the force increases six times.

750.

A current carrying conductor of certain length, kept perpendicular to the magnetic field experiences a force F. What will be the force if the current is increased four times, length is halved and magnetic field is tripled?

Answer»

F = ILB = (4I) × ( L / 2) × (3 B) = 6 F

Therefore, the force increases six times.

Discussion

Explore topic-wise InterviewSolutions in .

Interstellar space has an extremely weak magnetic field of the order of 1012T. Can such a weak field be of any significant consequence? Explain.

A magnetic needle of dipole moment `0.067 JT^(-1)` oscillates with a period of 2/3 s in a uniform magnetic field of 100 G . Find the moment of inertia of the needle about the axis of oscillations.

The magnetic field near the centre of a current carrying coil is uniform and ________A. parallel to the plane of coil.B. perpendicular to the plane of coilC. circularD. both (b) and (c)

Ratio between total intensity of magnetic field at equator to poles isA. `1:1`B. `1:2`C. `2:1`D. `1:4`

The lines joining the places of the same horizontal intensity are known asA. Isogonic linesB. Aclinic linesC. Isoclinic linesD. Isodynamic lines

The angle which are total magnetic field of earth makes with the surface of the earth is calledA. declinationB. magnetic meridianC. geographic meridianD. inclination

For soft iron, in comparison with steelA. hysteresis loss is moreB. hysterisis loss is sameC. hysteresis loss is lessD. hysterisis loss is negligible

Aclinic lines are the lines joining places ofA. zero dipB. equal dipC. zero declinationD. equal declination

`chi_(1)` and `chi_(2)` are susceptinilities of diamagnetic substance at temperatures `T_(1)K` and `T_(2)K` respectively. ThenA. `chi_(1)T_(1)=chi_(2)T_(2)`B. `chi_(1)=chi_(2)`C. `chi_(1)sqrt(T_(1))=chi_(2)sqrt(T_(2))`D. `chi_(1)T_(2)=chi_(2)T_(1)`

Define following terms in case of magnetic maps:i. Isomagnetic charts ii. Isodynamic lines iii. Isogonic lines iv. Aclinic lines

In a permamnent magnet at room temperatureA. magnetic moment of each molecules is zeroB. the individual molecules have non-zero magnetic moments which are all perfectly alignedC. domains are partially alignedD. domains are all perfectly aligned

Magnetic equator and geographical equator of the earth are same. Is this true or false?

Which of the following is an artificial magnet ?A. bar magnetB. Horse-shoe magnetC. magnetic needleD. all the above

A conducting wire can give magnetic pole when it is _________A. bent into the form of a circular ringB. placed in an external magnetic fieldC. suspended freely in airD. All the above

The strength of a magnetic field increases as _________A. the number of magnetic lines of force passing through a given area increasesB. strength of the magnetic poles increasesC. distance between the magnetic poles increasesD. does not exist

A point near the equator hasA. `B_(V)gtgtB_(H)`B. `B_(H)gtgtB_(V)`C. `B_(V)=B_(H)`D. `B_(V)=B_(H)=0`

Which of the following is a property shown by a magnet ?A. Attractive propertyB. Directive propertyC. IndcutionD. All the above

Two bar magnets are kept so that each magnet is in contact with another magnet as shown in the figure below. In which of the arrangements do the magnets lose magnetism faster ? Why ?

The magnetic field due to a bar magnet _____A. has the same direction at any pointB. is uniformC. is non-uniformD. does not exist

A line joining places of zero declination is calledA. agonicB. isoclinicC. isodynamicD. isogonal

A freely suspended magnet lies in the horizontal plane at ___________of earth.

Three identical thin bar magnets each of moment `M` are placed along three adjacent sides of a regular hexagon as shown in figure. The resultant magnetic moment of the system is A. `M`B. `Msqrt3`C. `Msqrt2`D. `2M`

The resultant magnetic moment for the following arrangement is A. `M`B. `2M`C. `3M`D. `4M`

The resultant magnetic moment for the following arrangement (non coplanar vectors) A. `M`B. `2M`C. `3M`D. `4M`

The point at which the resultant magnetic effect is zero is called _______

Resultant force acting on a diamagentic material in a magnetic field is in directionA. from stronger to the weaker part of the magnetic fieldB. from weaker to the strogner part of the magnetic fieldC. perpendicular to the magnetic fieldD. in the direction making `60^(@)` to the magnetic field

A magnetic needle lying parallel to a magnetic field requires `W units` of work to turn it through `60^(@)`. The torque needed to maintain the needle in this position will beA. `sqrt(3)W`B. WC. `(sqrt(3))/(2)W`D. 2W

If a magnet is hanged with its magnetic axis then it stops inA. Magnetic meridianB. Geometric meridianC. Angle of dipD. None of these

The magnetic lines of force inside a bar magnet:(A) Are from north-pole to south-pole of the magnet(B) Do not exist(C) Depend upon the area of cross-section of bar magnet(D) Are from south-pole to north-pole of magnet

Magnetic lines of force due to a bar magnet do not intersect becauseA. a point always has a single net magnetic fieldB. the lines have similar charges and so repel each otherC. the lines always diverge from a single pointD. None of the above

the magnetic lines of force inside a bar magnetA. Are from south-pole to north-pole of the magnetB. Are from north-pole to south-pole of the magnetC. Do not existD. Depend upon the area of cross-section of the bar magnet

Magnetic lines of force due to a bar magnet do not intersect becauseA. A point always has a single net magnetic fieldB. The lines have similar charges and so repel each otherC. The lines always diverge from a single pointD. The lines need magnetic lenses to be made to intersect

The magnet field lines due to a bar magnet are correctly shown inA. Intersect at the neutral pointB. Intersect near the poles of the magnetC. Intersect on the equatorial axis of the magnetD. Do not intersect at all

Two lines of force due to a bar magnetA. intersect at the neutral pointB. intersect near the poles of the magnetC. intersect on the equatorial axis of the magnetD. do not intersect at all

The magnetic susceptibility of a rod is `499`. The absolute permeability of vacuum is `4pixx10^(-7)H//m`. The absolute permeability of the material of the rod isA. `pixx10^(-4)H//m`B. `2pixx10^(-4)H//m`C. `3pixx10^(-4)H//m`D. `4pixx10^(-4)H//m`

The period of a thin magnet in a magnetic field is `2s`. It is cut into four equal parts by cutting it along length and breadth. The period of each of them in the same field isA. `1 s`B. `2 s`C. `3 s`D. `4 s`

Define magnetic flux.

When a charged particle enters a uniform magnetic field its kinetic energy-(a) remains constant (b) increases (c) decreases (d) becomes zero

Define magnetic flux density.

The unit of magnetic flux density is ………

Aproton enters a magnetic field of flux density 1.5 Wb/m2 with a speed of 2x 107 m/s at angle of 30° with the field. The force on the proton will be-(a) 0.24 x 10-12 N (b) 2.4 x 10-12 N (c) 24 x 10-12 N (d) 0.024 x 10-12 N

What are natural magnets?

How can the speed of rotation of a coil be increased? Write at least three methods.

Name some equipmetns that use electromagnetism for functioning.

Explain why the ozone layer is not affected by the Solar wind.

A current carrying conductor of certain length, kept perpendicular to the magnetic field experiences a force F. What will be the force if the current is increased four times, length is halved and magnetic field is tripled?