816 + Interview Questions in MAGNETISM IN GENERAL AWARENESS Page 10 InterviewSolution

451.	What is meant by line of force (line of flux)?
Answer» The line of force is the path that the north pole of a free magnetic needle would take around the bar magnet.

Discussion

452.	What are the objects affected by magnetic field?
Answer» Cellphone, Computer and DVD are the objects affected by magnetic field.

Discussion

453.	A magnet attracts ………a) wooden materials(b) any metal(c) copper(d) iron and steel
Answer» (d) iron and steel

Discussion

454.	One of the following is an example for a permanent magnet. (a) Electromagnet (b) Mumetal(c) Soft iron (d) Neodymium
Answer» (d) Neodymium

Discussion

455.	Name the material of core of an electromagnet for1. temporary magnet2. permanent magnet.
Answer» 1. They are made of soft iron. 2. They are made of iron, steel, cobalt, nickel or an alloy called ANILCO.

Discussion

456.	How will you make levitating propeller?
Answer» 1. Make a propeller from a 500-ml plastic bottle. Make a hole in the bottle lid. 2. Screw the lid with the hole on a bottle half filled with sand. Press fit a stiff straw in the lid. Embed the straw in the sand to make it stand erect. Place a few ring magnets in the straw. Similar poles will repel each other. 3. Place two magnets each inside and outside the propellor lid. These magnets will automatically stick to each other. 4. Like poles repel and this levitates the bottle fan. The ceiling fan makes it spin. 5. Place the propeller on the stiff straw. The magnets in the straw and the propeller should repel each other. This will make the propeller levitate. On placing it under a ceiling fan the propeller will spin very fast.

456.

How will you make levitating propeller?

Answer»

1. Make a propeller from a 500-ml plastic bottle. Make a hole in the bottle lid.

2. Screw the lid with the hole on a bottle half filled with sand. Press fit a stiff straw in the lid. Embed the straw in the sand to make it stand erect. Place a few ring magnets in the straw. Similar poles will repel each other.

3. Place two magnets each inside and outside the propellor lid. These magnets will automatically stick to each other.

4. Like poles repel and this levitates the bottle fan. The ceiling fan makes it spin.

5. Place the propeller on the stiff straw. The magnets in the straw and the propeller should repel each other. This will make the propeller levitate. On placing it under a ceiling fan the propeller will spin very fast.

Discussion

457.	What are the factors that the attractive force of two magnetic poles depend on?
Answer» The attractive force between the magnetic poles increases with increase in the strength of the pole and decreases with increase in the distance between the poles.

Discussion

458.	What is meant by atomic magnets?
Answer» Each atom of a magnetic substance is an independent magnet. They are called atomic magnets.

Discussion

459.	When an iron bar is moved over a bar magnet along its length the attractive force______A. increases first and then decreasesB. decreases first and then increasesC. remains sameD. increases
Answer» Correct Answer - B

Discussion

460.	Attractive property of a magnet is more at the……… (a) North pole (b) South pole (c) both a & b (d) middle
Answer» (d) both a & b

Discussion

461.	What are the difference in the magnetic properties of iron and steel?
Answer» Iron becomes a more intense magnet on magnetic induction. But that magnetic power is temporary. When the permanent magnet is removed it losses its magnetic power. In the presence of a magnet, steel doesn’t acquire the magnetic power like that of a soft iron. But steel retains most of its magnetic power after removing the permanent magnet. Iron gets magnetized faster but loses its magnetism as soon as the inducing magnet is removed. ... Steel is slow to be magnetized but retains the acquired magnetism for a long time. Steel is said to have low susceptibility but high retentivity. Steel is used for making magnets.

Discussion

462.	The permanent magnet is made fron which one of the following substances?A. Soft ironB. DiamagneticC. PAramagneticD. Ferromagnetic
Answer» Correct Answer - D

Discussion

463.	Ferromagnetic msterials owe their properties toA. vecant inner shellsB. Filled inner subshellsC. Partially vecant inner shellsD. Partially filled inner subshells
Answer» Correct Answer - D

Discussion

464.	A ferromagnetic material is heated above its curie temperature. Which one is a correct statement?A. Ferromagnetic domains are perfectly arrangedB. Ferromagnetic domains becomes randomC. Ferromagnetic domains are not influencedD. Ferromagnetic material changes itself into diamagnetic material
Answer» Correct Answer - B

Discussion

465.	At Curie point, a ferromagnetic material transforms into:A. non-magneticB. diamagneticC. paramagneticD. strong ferromagnetic
Answer» Correct Answer - C At Curie temperature , a ferromagnetic substance is converted into paramagnetic substance .

Discussion

466.	A current of 2 ampere is passed in a coil of radius 0.5 m and number of turns 20.The magnetic moment of the coil isA. `0.314 Am^(2)`B. `0.14A-m^(2)`C. `314A-m^(2)`D. `31.4A-m^(2)`
Answer» Correct Answer - D I=2A,r=0.5m,n=20,M=? M=nIA `nlpir^(2)` `20xx2xx3.14xx0.25` `=3.14Am^(2)`

Discussion

467.	The areas of cross-section of three magnets of same length are A,2AA and 6A respectively The ratio of their magnetic moments will beA. `6:2:1`B. `1:2:6`C. `1:4:36`D. `36:4:1`
Answer» Correct Answer - B M`oo`A `therefore M_(1):M_(2)M_(3)=A_(1):A_(2):A_(3)` `=A:2A:6A` =`1:2:6`

Discussion

468.	The magnetic field at a distance d from a short bar magnet in longitudinal and transverse positions are in the ratio.A. `1:1`B. `1:2`C. `2:1`D. `3:1`
Answer» Correct Answer - C `(B_("axis"))/(B_(eq))=((4pi)/(mu_(0))(2M)/r^(3))/(mu_(0)/(4pi)(M)/(r^(3)))=(2)/(1)`

Discussion

469.	The area enclosed by a hysteresis loop is a measure ofA. retentivityB. susceptibilityC. permeabilityD. energy loss per cycle
Answer» Correct Answer - D

Discussion

470.	A material produces a magnetic field which oppose the applied magnetic field, then it isA. daimagneticB. para magneticC. electro magneticD. ferro magnetic
Answer» Correct Answer - A

Discussion

471.	A material produces a magnetic field which oppose the applied magnetic field, then it isA. DiamagneticB. ParamagneticC. ElectromagneticD. Ferromagnetic
Answer» Correct Answer - A

Discussion

472.	Among the following properties describing diamagnetism identify the property that is wrongly statedA. Diamagnetic material do not have permanent magnetic momentB. Diamagnetism is explained in terms of electromagnetic inductionC. Diamagnetic materials have a small positive susceptibilityD. The magnetic moment of individual electrons neutralize each other
Answer» Correct Answer - C Diamagnetic materials have negative susceptibility . Thus (c) is wrongly stated .

Discussion

473.	Define magnetic inclination (I).
Answer» The angle subtended by the Earth’s total magnetic field B with the horizontal direction in the magnetic meridian is called dip or magnetic inclination (I) at the point.

Discussion

474.	Assertion: Cyclotron does not accelerate electron.Reason: Mass of the electron is very small(a) If both assertion and reason are true and the reason in the correct explanation of the assertion. (b) If both assertion and reason are true but the reason is not correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.(e) If assertion is false but reason is true.
Answer» (a) If both assertion and reason are true and reason is the correct explanation of assertion. Explanation: Cyclotron is suitable for accelerating heavy particles like protons, xparticles. etc. and not for electrons because of low mass.

474.

Assertion: Cyclotron does not accelerate electron.Reason: Mass of the electron is very small(a) If both assertion and reason are true and the reason in the correct explanation of the assertion. (b) If both assertion and reason are true but the reason is not correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.(e) If assertion is false but reason is true.

Answer»

(a) If both assertion and reason are true and reason is the correct explanation of assertion.

Explanation: Cyclotron is suitable for accelerating heavy particles like protons, xparticles. etc. and not for electrons because of low mass.

Discussion

475.	Define magnetic declination (D).
Answer» The angle between magnetic meridian at a point and geographical meridian is called the declination or magnetic declination (D).

Discussion

476.	Assertion: Cyclotron is a device which is used to accelerate the positive ion. Reason: Cyclotron frequency depends upon the velocity.(a) If both assertion and reason are true and the reason in the correct explanation of the assertion. (b) If both assertion and reason are true but the reason is not correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.(e) If assertion is false but reason is true.
Answer» (c) If assertion is true but reason is false. Explanation: Cyclotron is utilised to accelerate the positive ion. And cyclotron frequency is given by v = \(\frac{Be}{2πm}\) . It means cyclotron frequency doesn’t depends upon velocity.

476.

Assertion: Cyclotron is a device which is used to accelerate the positive ion. Reason: Cyclotron frequency depends upon the velocity.(a) If both assertion and reason are true and the reason in the correct explanation of the assertion. (b) If both assertion and reason are true but the reason is not correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.(e) If assertion is false but reason is true.

Answer»

(c) If assertion is true but reason is false.

Explanation: Cyclotron is utilised to accelerate the positive ion. And cyclotron frequency is given by v = \(\frac{Be}{2πm}\) . It means cyclotron frequency doesn’t depends upon velocity.

Discussion

477.	Magnetic meridian is an imaginary:A. pointB. horizontal planeC. vertical planeD. line along N-S
Answer» Correct Answer - C Magnetic meridian is a vertical plane.

Discussion

478.	Lines which represent places of constant angle of dip are calledA. isobaric linesB. isogonic linesC. isoclinic linesD. isodynamic lines
Answer» Correct Answer - C Lines which represent places of constant angle of dip are called isoclinic lines.

Discussion

479.	Match the following:1. Directive property(a) Never intersect2. Magnetic poles(b) Magnetic compass3. Lines of force(c) Attract4. Unlike poles(d) Exist in pairs
Answer» 1. b 2. d 3. a 4. c

479.

Match the following:1. Directive property(a) Never intersect2. Magnetic poles(b) Magnetic compass3. Lines of force(c) Attract4. Unlike poles(d) Exist in pairs

Answer»

1. b

2. d

3. a

4. c

Discussion

480.	What is the other name of lodestone?
Answer» Magnetite. (Iron oxide)

Discussion

481.	With a standard rectangular bar magnet, the time period in the uniform magnetic field is `4 sec`. The bar magnet is cut parallel to its length into `4` equal pieces. The time period in the uniform magnetic field when the piece is used (in sec) (bar magnet breadth is small)A. `16`B. `8`C. `4`D. `2`
Answer» Correct Answer - B `T=2pisqrt ((I)/(MB)),I=(m)/(12)(l^(2)+B^(2))`

Discussion

482.	A bar magnet of moment of inertia `1xx10^(-2)kgm^(2)` vibrates in a magnetic field of induction `0.36xx10^(-4)` tesla. The time period of vibration is `10s`. Then the magnetic moment of the bar magnet is `(Am^(2))`A. `120`B. `111`C. `140`D. `160`
Answer» Correct Answer - B `M=4pi^(2)(I)/(T^(2)B)`

Discussion

483.	The magnetic field at a point x on the axis of a small bar magnet is equal to the field at a point y on the equator of the same magnet. The ratio of the distances of `x` and `y` from the centre of the magnet isA. `2^(-3)`B. `2^(-1//3)`C. `2^(3)`D. `2^(1//3)`
Answer» Correct Answer - D

Discussion

484.	The distance of two points on the axis of a magnet from its centre is `10 cm` and `20 cm` repectively. The ratio of magnatic intensity at these points is `12.5 : 1`. The length of the megnet will beA. 5 cmB. 25 cmC. 10 cmD. 20 cm
Answer» Correct Answer - C

Discussion

485.	The field due to a magnet at a distance `R~ from the centre of the magnet is proportionalA. `R^(2)`B. `R^(3)`C. `1//R^(2)`D. `1//R^(3)`
Answer» Correct Answer - D

Discussion

486.	Curie-Weiss law is obeyed by iron at a temperature….A. at Curie temeprature onlyB. at all temperatureC. below Curie temperatureD. above Curie temperature
Answer» Correct Answer - D Iron is a ferromagnetic substance and ferromagnetic substance obeys Curie- Weiss law above its Curie temperature .

Discussion

487.	The magnetic potential at a point at a distance r from its centre along its axis is V.The magnetic potential at a point at the distance 2 r will beA. VB. 2VC. V/2D. V/4
Answer» Correct Answer - D `V_(1)=V,r_(1)=r, r^(2)=2r, V_(2)=?` `V oo (1)/(r^(2))` `(V_(2))/(V_(1))=((r)/(2r))^(2)V_(1)=(V)/(4)`

Discussion

488.	Keeping r constant a graph is plotted by varying both 0 and the potential V due to the magnetic dipole.Which is a correct graph in the figure given below?A. B. C. D.
Answer» Correct Answer - B The graph of cosine function

Discussion

489.	Force between two unit pole strength placed at a distance of one metre isA. 1 NB. `(10^(-7))/(4pi)N`C. `10^(-7)N`D. `4pixx10^(-7)N`
Answer» Correct Answer - C

Discussion

490.	A small bar magnet of moment M is placed in a uniform field H. If magnet makes an angle of `30^(@)` with field, the torque acting on the magnet isA. MHB. `(MH)/(2)`C. `(MH)/(3)`D. `(MH)/(4)`
Answer» Correct Answer - B

Discussion

491.	A bar magnet of magnetic moment `10-J//T` is free to rotate in a horizontal plane. The work done in rotating the magnet slowly from a direction parallel to a horizontal magnetic field of `4x×10` T to a direction `60^(o)` from the field will beA. 0.2 JB. 2.0 JC. 4.18 JD. `2xx10 J`
Answer» Correct Answer - A

Discussion

492.	The relation between `mu` and `H` for a specimen of iron is `mu=[(0.4)/(H)+12xx10^(-4)]henry//metre`. The value of `H` which produces flux density of `1` tesla will beA. `250A//m`B. `500A//m`C. `750A//m`D. `10^(3)A//m`
Answer» Correct Answer - B `B = muH` `B = [(0.4)/(H) + 12x10^(-4)]H`

Discussion

493.	Vibration of suspended magnet works on the principle ofA. torque acting on the bar magnetic and rotational inertiaB. force acting on the bar magnet and rotational inertiaC. both the force and torque acting on the bar magnetD. neither force nor torque
Answer» Correct Answer - A

Discussion

494.	Name the unit used to measure magnetic field.A. ThermometerB. PyrameterC. HygrometerD. Fluxmeter
Answer» Correct Answer - D

Discussion

495.	An iron specimen has relative permeability of `600` when placed in uniform magnetic field of intensity `110 amp//m`. Then the magnetic flux density inside is……tesls.A. `18.29xx10^(-3)`B. `8.29xx10^(-2)`C. `66xx10^(3)`D. `7.536xx10^(-4)`
Answer» Correct Answer - B `B=mu_(0)mu_(r)H`

Discussion

496.	If a paramagnetic liquid is placed in a watch glass,resting on the pieces,the liquid accumulates where the field isA. ZeroB. WeakC. StrongD. None of these
Answer» Correct Answer - C

Discussion

497.	The figure shows two diamagnetic spheres located near the south pole of a bar magnet. Then, A. the force on sphere `1` directed towards the magnetB. the force on sphere `2` is directed away from the magnetC. the magnetic dipole moment of sphere is directeed towards the magnetD. the magnetic diple moment of sphere `2` is directed away form the magnet.
Answer» Correct Answer - B::D Diamagnetic material gets repelled by magnet, and so both the spheres will be repelled by the magnet. The dipole moment of spheres also directed away from the magnet.

Discussion

498.	A watch glass containing some powdered substance is placed between the pole pieces of a magnet. Deep concavity is observed at the centre. The substance in the watch glass isA. ironB. chromiumC. carbonD. wood
Answer» Correct Answer - A

Discussion

499.	In a non uniform field,the specimen of the paramagnetic substance rotates until its longest axis isA. VerticalB. HorizontalC. Parallel to fieldD. Perpendicular to field
Answer» Correct Answer - C

Discussion

500.	If a diamagnetic liquid is placed in a watch glass on the pole pieces of a magnet, then the liquid will accumulate atA. CentreB. EndsC. At some placeD. None of these
Answer» Correct Answer - B

Discussion

Explore topic-wise InterviewSolutions in .

What is meant by line of force (line of flux)?

What are the objects affected by magnetic field?

A magnet attracts ………a) wooden materials(b) any metal(c) copper(d) iron and steel

One of the following is an example for a permanent magnet. (a) Electromagnet (b) Mumetal(c) Soft iron (d) Neodymium

Name the material of core of an electromagnet for1. temporary magnet2. permanent magnet.

How will you make levitating propeller?

What are the factors that the attractive force of two magnetic poles depend on?

What is meant by atomic magnets?

When an iron bar is moved over a bar magnet along its length the attractive force______A. increases first and then decreasesB. decreases first and then increasesC. remains sameD. increases

Attractive property of a magnet is more at the……… (a) North pole (b) South pole (c) both a &amp; b (d) middle

What are the difference in the magnetic properties of iron and steel?

The permanent magnet is made fron which one of the following substances?A. Soft ironB. DiamagneticC. PAramagneticD. Ferromagnetic

Ferromagnetic msterials owe their properties toA. vecant inner shellsB. Filled inner subshellsC. Partially vecant inner shellsD. Partially filled inner subshells

A ferromagnetic material is heated above its curie temperature. Which one is a correct statement?A. Ferromagnetic domains are perfectly arrangedB. Ferromagnetic domains becomes randomC. Ferromagnetic domains are not influencedD. Ferromagnetic material changes itself into diamagnetic material

At Curie point, a ferromagnetic material transforms into:A. non-magneticB. diamagneticC. paramagneticD. strong ferromagnetic

A current of 2 ampere is passed in a coil of radius 0.5 m and number of turns 20.The magnetic moment of the coil isA. `0.314 Am^(2)`B. `0.14A-m^(2)`C. `314A-m^(2)`D. `31.4A-m^(2)`

The areas of cross-section of three magnets of same length are A,2AA and 6A respectively The ratio of their magnetic moments will beA. `6:2:1`B. `1:2:6`C. `1:4:36`D. `36:4:1`

The magnetic field at a distance d from a short bar magnet in longitudinal and transverse positions are in the ratio.A. `1:1`B. `1:2`C. `2:1`D. `3:1`

The area enclosed by a hysteresis loop is a measure ofA. retentivityB. susceptibilityC. permeabilityD. energy loss per cycle

A material produces a magnetic field which oppose the applied magnetic field, then it isA. daimagneticB. para magneticC. electro magneticD. ferro magnetic

A material produces a magnetic field which oppose the applied magnetic field, then it isA. DiamagneticB. ParamagneticC. ElectromagneticD. Ferromagnetic

Define magnetic inclination (I).

Define magnetic declination (D).

Magnetic meridian is an imaginary:A. pointB. horizontal planeC. vertical planeD. line along N-S

Lines which represent places of constant angle of dip are calledA. isobaric linesB. isogonic linesC. isoclinic linesD. isodynamic lines

Match the following:1. Directive property(a) Never intersect2. Magnetic poles(b) Magnetic compass3. Lines of force(c) Attract4. Unlike poles(d) Exist in pairs

What is the other name of lodestone?

With a standard rectangular bar magnet, the time period in the uniform magnetic field is `4 sec`. The bar magnet is cut parallel to its length into `4` equal pieces. The time period in the uniform magnetic field when the piece is used (in sec) (bar magnet breadth is small)A. `16`B. `8`C. `4`D. `2`

A bar magnet of moment of inertia `1xx10^(-2)kgm^(2)` vibrates in a magnetic field of induction `0.36xx10^(-4)` tesla. The time period of vibration is `10s`. Then the magnetic moment of the bar magnet is `(Am^(2))`A. `120`B. `111`C. `140`D. `160`

The magnetic field at a point x on the axis of a small bar magnet is equal to the field at a point y on the equator of the same magnet. The ratio of the distances of `x` and `y` from the centre of the magnet isA. `2^(-3)`B. `2^(-1//3)`C. `2^(3)`D. `2^(1//3)`

The distance of two points on the axis of a magnet from its centre is `10 cm` and `20 cm` repectively. The ratio of magnatic intensity at these points is `12.5 : 1`. The length of the megnet will beA. 5 cmB. 25 cmC. 10 cmD. 20 cm

The field due to a magnet at a distance `R~ from the centre of the magnet is proportionalA. `R^(2)`B. `R^(3)`C. `1//R^(2)`D. `1//R^(3)`

Curie-Weiss law is obeyed by iron at a temperature….A. at Curie temeprature onlyB. at all temperatureC. below Curie temperatureD. above Curie temperature

The magnetic potential at a point at a distance r from its centre along its axis is V.The magnetic potential at a point at the distance 2 r will beA. VB. 2VC. V/2D. V/4

Keeping r constant a graph is plotted by varying both 0 and the potential V due to the magnetic dipole.Which is a correct graph in the figure given below?A. B. C. D.

Force between two unit pole strength placed at a distance of one metre isA. 1 NB. `(10^(-7))/(4pi)N`C. `10^(-7)N`D. `4pixx10^(-7)N`

A small bar magnet of moment M is placed in a uniform field H. If magnet makes an angle of `30^(@)` with field, the torque acting on the magnet isA. MHB. `(MH)/(2)`C. `(MH)/(3)`D. `(MH)/(4)`

A bar magnet of magnetic moment `10-J//T` is free to rotate in a horizontal plane. The work done in rotating the magnet slowly from a direction parallel to a horizontal magnetic field of `4x×10` T to a direction `60^(o)` from the field will beA. 0.2 JB. 2.0 JC. 4.18 JD. `2xx10 J`

The relation between `mu` and `H` for a specimen of iron is `mu=[(0.4)/(H)+12xx10^(-4)]henry//metre`. The value of `H` which produces flux density of `1` tesla will beA. `250A//m`B. `500A//m`C. `750A//m`D. `10^(3)A//m`

Vibration of suspended magnet works on the principle ofA. torque acting on the bar magnetic and rotational inertiaB. force acting on the bar magnet and rotational inertiaC. both the force and torque acting on the bar magnetD. neither force nor torque

Name the unit used to measure magnetic field.A. ThermometerB. PyrameterC. HygrometerD. Fluxmeter

An iron specimen has relative permeability of `600` when placed in uniform magnetic field of intensity `110 amp//m`. Then the magnetic flux density inside is……tesls.A. `18.29xx10^(-3)`B. `8.29xx10^(-2)`C. `66xx10^(3)`D. `7.536xx10^(-4)`

If a paramagnetic liquid is placed in a watch glass,resting on the pieces,the liquid accumulates where the field isA. ZeroB. WeakC. StrongD. None of these

A watch glass containing some powdered substance is placed between the pole pieces of a magnet. Deep concavity is observed at the centre. The substance in the watch glass isA. ironB. chromiumC. carbonD. wood

In a non uniform field,the specimen of the paramagnetic substance rotates until its longest axis isA. VerticalB. HorizontalC. Parallel to fieldD. Perpendicular to field

If a diamagnetic liquid is placed in a watch glass on the pole pieces of a magnet, then the liquid will accumulate atA. CentreB. EndsC. At some placeD. None of these

Attractive property of a magnet is more at the……… (a) North pole (b) South pole (c) both a & b (d) middle