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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 751. |
What is the connection between electricity and magnetism? |
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Answer» Electricity and magnetism are closely related to each other. The current flowing through the wire produces a circular magnetic field outside the wire. The direction of this magnetic field depends on the electric current. Similarly, a changing magnetic field produces an electric current in a wire or conductor. The relationship between electricity arid magnetism is called electromagnetism. |
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| 752. |
A conductor of length 50 cm carrying a current of 5 A is placed perpendicular to a magnetic field of induction 2 × 10-3 T. Find the force on the conductor |
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Answer» Force on the conductor = ILB = 5 × 50 × 10-2 × 2 × 10-3 = – 5 × 10-3 N |
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| 753. |
State Fleming’s Left Hand Rule. |
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Answer» It states that while stretching the three fingers of left hand in perpendicular manner with each other, if the direction of the current is denoted by middle finger of the left hand and the second finger is for direction of the magnetic field then the thumb of the left hand denotes the direction of the force or movement of the conductor |
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| 754. |
Match the following :Column - IColumn - II1. Magnetic material(a) Oersted2. Non - magnetic material(b) Iron3. Current and magnetism(c) induction4. Electromagnetic induction(d) Wood5. Electric generator(e) Faraday |
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Answer» 1. (b) iron 2. (d) wood 3. (a) Oersted 4. (e) Faraday 5. (c) induction |
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| 755. |
Differentiate step up and step down transformer. |
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Answer»
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| 756. |
True or False :1. A generator converts mechanical energy into electrical energy 2. Magnetic field lines always repel each other and do not intersect 3. Fleming’s Left hand rule is also known as Dynamo rule4. The speed of rotation of an electric motor can be increased by decreasing the area of the coil5.A transformer can step up direct current6. In a step down transformer the number of turns in primary coil is greater than that of the number of turns in the secondary coil |
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Answer» 1. True 2. True 3. True 4. False - The speed of rotation of coil can be increased by increasing the are of the coil. 5. False - A transformer can step up alternating current 6. True |
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| 757. |
Transformer works on (a) AC only (b) DC only (c) both AC and DC (d) AC nor effectively than DC |
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Answer» Correct answer is (a) AC only |
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| 758. |
List the main parts of an electric motor. |
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Answer» Main parts of an electric motor are: 1. Shaft, 2. Primary and Secondary windings, 3. Ball bearings, 4. Armature, 5. Stator, 6. Commutator, 7. Brushes, 8. Terminals |
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| 759. |
Which of the following converts electrical energy into mechanical energy? (a) motor (b) battery (c) generator (d) switch |
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Answer» Correct answer is (a) motor |
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| 760. |
A magnetised wire is bent into an arc of a circle subtending an angle `90^(0)` at its centre then its manetic moment will beA. `(xsqrt2)/(3)`B. `(x)/(3)`C. `((2sqrt2)x)/(3)`D. `(3x)/(2sqrt2)` |
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Answer» Correct Answer - C `M^(1)=(2M sin((theta)/(2)))/(theta)` |
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| 761. |
A magnetised steel wire `31.4cm` long has a pole strength of `0*2Am`. It is bent in the form of a semicircle. Calcualte its magnetic moment. |
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Answer» Correct Answer - `0.04 Am^(2)` |
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| 762. |
A thin rod `30 cm` long is uniformly magnetised and its period of oscillation is `4 s`. It is broken into three equal parts normal to its length. The period of oscillation of each part isA. `12 s`B. `6s`C. `1.33s`D. `2.66s` |
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Answer» Correct Answer - C `T=2pisqrt((i)/(MB)` |
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| 763. |
A thin rod `30 cm` long is uniformly magnetised and its period of oscillation is `4 s`. It is broken into three equal parts normal to its length. The period of oscillation of each part is |
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Answer» Correct Answer - 1.33 s |
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| 764. |
The relation between magnetic induction(B),magnetising field (H)And the magnetisation (I) isA. `B=mu_(0)(H+1)`B. B=(H+1)C. `B=mu_(0)(H-1)`D. `B=mu_(0) l(H=1)` |
| Answer» Correct Answer - A | |
| 765. |
The ratio of magnetic induction (B)to the strength of magnetising field is calledA. Magnetic permeabilityB. Magnetic subsceptibilityC. Intensity of magnetisationD. Magnetic flux density |
| Answer» Correct Answer - A | |
| 766. |
A specimen of iron is uniformly magnetised by a magnetising field of `500Am^(-1)` . If the magnetic induction in the specimen is `0.2Wbm^(-2)`. The susceptibility nearly isA. `317.5`B. `418.5`C. `217.5`D. `175` |
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Answer» Correct Answer - A `B=muH=mu_(0)mu_(r)H,chi=mu_(r)-1` |
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| 767. |
The variation of magnetic susceptibility `(chi)` with temperature for a diamagnetic substance is best represented byA. B. C. D. |
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Answer» Correct Answer - B |
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| 768. |
The variation of magnetic susceptibility `(chi)` with temperature for a diamagnetic substance is best represented byA. B. C. D. |
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Answer» Correct Answer - B For diamagnetic material `chi` is `-ve &` independent of temperature |
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| 769. |
The magnetic susceptibility is negative forA. paramagnetic material onlyB. ferromagnetic material onlyC. paramagnetic and ferromagnetic meterialsD. diamagnertic meterial only |
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Answer» Correct Answer - D |
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| 770. |
A bar magnet is hung by a thin cotton thread in a uniform horizontal magnetic field and is in equilibrium state. The energy required to rotate it by 60^(@) is W. Now the torrue required to keep the magnet in this new position isA. `(W)/(sqrt3)`B. `sqrt3W`C. `(sqrt3W)/(2)`D. `(2W)/(sqrt3)` |
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Answer» Correct Answer - B |
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| 771. |
Alnico is used for making permanent magnets becoause it hasA. High coercivity and high retentivityB. high coercivity and low retentivityC. low coercivity and low retentivityD. low coercivity and high retentivity |
| Answer» Correct Answer - A | |
| 772. |
The susceptibility of a diamagnetic substance isA. `oo`B. zeroC. small but negativeD. small but positive |
| Answer» Correct Answer - C | |
| 773. |
Liquids and gases never exhibitA. diamagnetic propertiesB. para magnetic propertiesC. ferro magnetic propertiesD. electro magnetic properties |
| Answer» Correct Answer - C | |
| 774. |
A bar magnet of `5 cm` long having a pole strenght of `20 A.m`. Is deflected through `30^(@)` from the magnetic meridian. If `H=(320)/(4pi)A//m`, the deflecting couple isA. `1.6xx10^(-4)Nm`B. `3.2xx10^(-5)Nm`C. `1.6xx10^(-5)Nm`D. `1.6xx10^(-2)Nm` |
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Answer» Correct Answer - C `C=M mu_(0)H sin theta` |
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| 775. |
At curie temprature,the ferromagnetic meterialA. Loses its ferromagnetismB. Develops reverse polarityC. Has maximum subsceptibilityD. Has susceptibility equal to zero |
| Answer» Correct Answer - A | |
| 776. |
Two identical "bar" magnets are jouned to form a cross. If this conbination is suspended freely in a uniform field the angles made by the magnets with field direction are respectivelyA. `60^(@),30^(@)`B. `37^(@),53^(@)`C. `45^(@),45^(@)`D. `mB cot theta` |
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Answer» Correct Answer - C `tau=MB sin theta,tau_(1)=tau_(2)` |
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| 777. |
Write your inferences.a. All magnets have same shape. b. All magnets show N, S direction when suspended freely. c. All magnets are man made. d. All magnets show N, S direction when suspended freely. |
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Answer» a. No, There are different types of magnets. b. Yes, Because the north pole of magnet turns to geographical south of earth and south pole turns to geographical north of earth. c. No, There are natural and man made magnets. d. Yes. Earth acts like a large magnet. Hence the poles of the suspended magnet is opposite to the poles of the earth’s magnet. |
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| 778. |
Give the uses of magnets |
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Answer» 1. Magnets are used in speakers to power up. 2. Magnets are used in Ladies hand bags, Pencil boxes etc., to make a tight seal. 3. Magnets are also used in some door lock 4. In home, magnets are used as magnetic toys, magnetic smiley stickers, magnetic Alphabet stickers to stick on the refrigerators. 5. Magnets are used to store data in computers. |
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| 779. |
Give any two tips to store bar magnets |
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Answer» 1. Bar magnet should be kept in pairs with their unlike poles on the same side. 2. They must be seperated by a piece of wood and two pieces of soft iron should be placed across their ends. |
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| 780. |
When an iron nail is wounded with copper wire and connected to a battery, it doesn’t become a magnet, select the reasons from the following.a. Battery has not enough charge. b. The insulation at the ends of the wire is not removed. c. The nail is wounded with non insulated copper wire. d. The polarity of the battery is changing. |
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Answer» Answer is a, b ,c |
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| 781. |
The pole of a magnet attracts an iron nail which has no magnetic power. Describe the working behind this. |
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Answer» The magnet attracts the iron nail brought near the pole of a magnet really as the result of magnetic induction. If the magnetic material reaches near the magnetic field of the magnet, an unlike pole is induced at its near end. The pole of permanent magnet is attract the newly formed unlike poles. That is why the magnetic pole attracts a magnetic material near it. |
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| 782. |
An Iron nail is suspended at the north pole of a bar magnet. Bring the north pole of another magnet near the free end of a nail. What is observed? What is its reason? |
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Answer» The free end of an iron nail repel. Because the free end of an iron nail becomes north pole by magnetic induction. |
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| 783. |
Explain the attraction and repulsion between magnetic poles. |
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Answer» 1. Like poles (N – N, S – S) repel each other. 2. Unlike poles (N – S, S – N) attract each other. |
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| 784. |
______ poles repel to each other.i. N – Nii. N – Siii. S – Niv. S – S(a) i and ii(b) ii and iii(c) iii and iv(d) i and iv |
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Answer» (d) i and iv |
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| 785. |
When N pole of bar magnet is moved closer to the north pole of a magnet it will(a) attract(b) repel(c) rotate(d) none |
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Answer» Correct answer is (b) repel |
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| 786. |
The phenomenon of lagging of magnetic induction behind the magnetising field is called ……… |
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Answer» The phenomenon of lagging of magnetic induction behind the magnetising field is called hysteresis. |
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| 787. |
LET US MAKE MAGNETSTake a nail / a piece of Iron and place it on a table. Now take a bar magnet and place one of its poles near one edge of the nail/piece of Iron and rub from one end to another end without changing the direction of the pole of the magnet. Repeat the process for 30 to 40 times.Bring a pin or some iron filings near the nail/piece of Iron to check whether it has become a magnet. Does the nail/piece of iron attract the pin/iron filings? If not, continue the same process for some more time. |
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Answer» Yes, The nail / a piece of Iron acquires the same ability to attract other pieces of pin/ iron filings. |
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| 788. |
True or False. If False, give the correct statement:1. A cylindrical magnet has only one pole.2. Similar poles of a magnet repel each other.3. Maximum iron filings stick in the middle of a bar magnet when it is brought near them.4. A compass can be used to find East-West direction at any place.5. Rubber is a magnetic material. |
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Answer» 1. False. A cylindrical magnet has two poles 2. True. 3. False. Maximum iron filings stick in the poles of a bar magnet when it is brought near them. 4. True. A magnetic compass always points towards the North-South direction. If the North-South direction is known, then the East-West direction can also be determined. This direction is perpendicular to the North-South direction, ie., perpendicular to the compass needle in the same plane. 5. False. Rubber is anon-magnetic material |
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| 789. |
The substances which are strongly attracted by the magnet areA. DiamagnticB. ParamagneticC. FerromagneticD. Electromagnetic |
| Answer» Correct Answer - C | |
| 790. |
For protecting a sensitive equipment from the external magnetic field, it should beA. placed inside an aluminium canB. placed inside an iron canC. wrapped with insulation around it when passing current through itD. surrounded with fine copper sheet |
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Answer» Correct Answer - B |
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| 791. |
The magnetic field used to magnetise a material is called the ……… |
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Answer» The magnetic field used to magnetise a material is called the magnetic intensity. |
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| 792. |
A diamagnetic substance is brought near a strong magnet, then it isA. attracted by a magnetB. repelled by a magnetC. repelled by North pole and attracted by South poleD. attracted by North pole and repelled by South pole |
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Answer» Correct Answer - B |
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| 793. |
You are provided with an iron needle. How will you magnetize it? |
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Answer» 1. Place the iron needle on the table. 2. Take a bar magnet and place one of its poles near one edge of the iron needle. 3. Rub from one end to another without changing the direction of the pole of the magnet. 4. Repeat the process for 30 to 40 times. The needle will be magnetized. 5. If it will not attract pin or iron fillings continue the same process for some more time. |
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| 794. |
A cell having an emf of 2 V and internal resistance of `0.5 Omega` is sending current through a tangent galvanometer of resistance `4.5 Omega`. If another external resistance of `95 Omega` is introducedm the deflection of the galvanometer is `45^(@)` , calculate the reduction factor fof the galvanometer? |
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Answer» Correct Answer - 0.02 A |
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| 795. |
The period of oscillations of a magnetic needle in a magnetic field is 1.0 sec. If the length of the needle is halved by cutting it, the time perood will beA. 1.0 secB. 0.5 secC. 0.25 secD. 2.0 sec |
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Answer» Correct Answer - B |
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| 796. |
Arrange the following statement is sequential order to magnetize a steel bar using single touch method. (a) Once, it has reached the other end, lift the magnet away from the steel bar and again bring it to the starting point. (b) Keep a steel bar to be magnetized on a wooden table. (c) Take a strong magnet and bring one of the poles of the magnet near one end of the steel bar and gently rub from one end to the other end. (d) Repeat this process several times.A. bcadB. bacdC. cbdaD. cabd |
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Answer» Correct Answer - A (a) Keep a steel bar to be magnetized on a wooden table (b) (b) Take a strong magnet and bring one of the poles of the magnet near one end of the steel bar and gently rub from one end to the other end (c) (c) Once, it has reached the other end, lift the magnet away from the steel bar and again bring it to the starting point (a) Repeat this process several times (d) |
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| 797. |
Arrange the following statement in sequential order the process of plotting the lines of force around a bar magnet. (a) Draw a line in the middle of a white paper fixed on a drawing board. (b) Repeat the procedures described above, by shifting the compass and plot the points 2,3,4 , etc. (c) Place a bar magnet NS on the line so that its axial line coincides with the line on the paper and mark its boundary. (d) Join the points 0,1,2,3,....by a smooth curve. (e) Take a plotting compass and place it such that its south pole is directed towards point 0 at the edge of the bar magnet, and mark point 1 in the direction in which the north pole of the plotting compass points.A. acebdB. abcedC. ebcadD. eabcd |
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Answer» Correct Answer - A (a) Draw a line in the middle of a white paper fixed on a drawing board. (b) Place a bar magnet NS on the line on the paper and mark its boundary. (C) take a plotting compass and place it such that its south pole is directed towards point 0 at the edge of the bar magnet and mark point 1 in the direction in which the north pole of the plotting compass points. (d) Repeat the procedure described above by shifting the compass and plot the points 2,3,4. etc. (e) Join the points 0,1,2,3,.... by a smooth curve. |
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| 798. |
The time period of oscillation of a bar magnet suspended horizontaliy along the magnetic meridian is `T_(0)`. If this magnet is replaced by another magnet of the same size and pole strength but with double the mass, the new time period will beA. `(T_(0))/(2)`B. `(T_(0))/(sqrt(2))`C. `sqrt(2)T_(0)`D. `2T_(0)` |
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Answer» Correct Answer - C |
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| 799. |
When `sqrt(3)` ampere current is passed in a tangent galvanometer, there is a deflection of `30^(@)` in it. The deflection obtained when 3 amperes current is passed, isA. `30^(@)`B. `45^(@)`C. `60^(@)`D. `75^(@)` |
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Answer» Correct Answer - B |
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| 800. |
Two tangent galvanometer P and Q differ only in the number of turns of their coils and are connected in series. On passing a current through them, the deflections in P and Q are found to gbe `45^(@)` and `35^(@)` respectively. Calculate the ratio of the number of turns |
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Answer» Correct Answer - `10:7` |
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