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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.
| 701. |
Which of the following isotopes of uranium is unstable? |
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Answer» U-234 |
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| 702. |
(i) Ravi kept a book at a distance of 10 cm from the eyes of his friend Hari. Hari is not able to read anything written on the book. Explain why? (ii) A lens of focal length 5.0 cm is being used by a student in the laboratory as a magnifying glass. His least distance of distinct vision is 25 cm. What magnification is the student getting? |
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Answer» SOLUTION :(i) Because least distance of distinct VISION is 25 cm, and book is kept at a distance of 10 cm. (ii) `U=?, v=-25cm, f=5cm`. `(1)/(f)=(1)/(v)-(1)/(u)` `(1)/(5)=(1)/((-25))-(1)/(u)` `(1)/(u)=(1)/((-25))-(1)/(5)` `u=(-25)/(6)` `m=(v)/(u)` `m=(-25)xx(6)/(-25)` `m=6` |
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| 703. |
The human eye can focus objects at different distances by adjusting the focal length of the eye lens. This is due to. |
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Answer» presbyopia |
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| 704. |
Draw an appropriate schematic diagram showing common domestic circuits and discuss the importance of fuse. Why is it that a burnt out fuse should be replaced by another fuse of identical rating? |
Answer» Solution : A fuse in a circuit prevents damage to the appliances and the circuit DUE to overloading. Otherwise, the appliances or the circuit MAY be damaged. When current in the circuit exceeds the value of fuse rating, the fuse wire burns due to overloading. This causes a gap in the circuit and the current STOPS flowing in the circuit. This is done to the reason so that the circuit or the appliances to be connectedin the circuit continue FUNCTIONING without any damage in future. |
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| 705. |
Describlethe constructionand workingof an AC generator ( an alternator). |
Answer» Solution :An electric genertor is a devicethat converts mechanical energyinto electrical energy . Itsworking is basedon electromagneticinduction.  Construction : (1) Figure13.30 (a) shownsthe constructionof an AC generator . Itconsists of a rectangularcoilABCD placedbetweenthe twopoles of a permgent mganet . (2) Two ends of this coilare connected to the two metal (copper) rings`R_(1)`and `R_(2)`. Theinner side of theseringsare insulated . (3) The twoconductingstationary brushed `B_(1)` and `B_(2)` are kept pressedseparatelyon the rings `R_(1)`and `R_(2)`respectively . (4) The tworings `R_(1)` and `R_(2)`areinternallyattachedto an axle .Theaxlemay be mechanicallyrotated to from outsidetorotate the COIL inside the mgneticfield . (5) Outerendsof the twobrushes are connected to thegalvanometerto showthe flowof currentin the given external circuit . Working : (1) Suppose, theaxleattached to thetworingsis rotatedsuchthat the arm AB moves up and the arm CDmoves down in the magneticfield produced by the permanent magnet . THENTHE coil ABCD rotates clockwisein the arrangement SHOWN in the figure . By applying Fleming.s right hand rule , we findthat the induced currents areset upin thse arms along thedirectionAB and CD . Thismeans that the currentin external circuit flows from brush `B_(2)`to `B_(1)` [Ifthe COILIS madeof largenumberof turns,the currentgeneratedin eachturn adds up to givea largecurrentthrough the coil] . (2) Afterhalfa rotation , arm CD startsmovingup and AB movingdown .Asaresult ,the directionof the inducedcurrentsin both the arms change , givingrise tothe net induced current in the direction DCBA . Thismeans that the currentin theexternalcircuitnow flows from brush `B_(1)` to `B_(2)` (3) Thus, after everyhalf rotation the directionof the currentin the respective arms changes. Sucha current ,whichchanges directionafter equal INTERVAL of time, is calledan alternatingcurrent (abbreviated as AC). |
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| 706. |
The following 'precautions' were listed by a student in the experiment on study of 'Dependence of current on potential difference'. (A) Use copper wires as thin as possible for making connections. (B) All the connections should be kept tight. (C) The positive and negative terminals of the voltmeter and the ammeter should be correctly connected. (D) The 'zero error' in the ammeter and the voltmeter should be noted and taken into consideration while recording the measurements. (E) The 'key' in the circuit, once plugged in, should not be taken out till all the observations have been completed. The 'precautions' that need to be corrected and revised are : |
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Answer» (A), (C) and (E) |
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| 707. |
What will be the equivalent resistance between points A and B of the following electric circuit? |
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Answer» `1 OMEGA`  As all resistors are CONNECTED in series, their equivalent resistance, `R_s = 2 + 2 + 2 +2 +2 = 10 Omega` |
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| 708. |
The mass of a body is measured on planet Earth as M kg. When it is taken to a planet of radius halfthat of the Earth then its value will be ___________ kg. |
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Answer» 4M |
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| 709. |
Primary of a transformer has 20,000 turns and the secondary has 30,000 turns. 160V AC is applied at the primary ofthe transformer? How much power must be supplied to the primary of the transformer so that 5OOW power is ôbtained from secondary?. |
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Answer» |
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| 710. |
(a) Describe an activity along with a labelled diagram the phenomenon of dispersion through a prism. (b) Explain in brief the formation of rainbow with the help of figure. |
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Answer» Solution :(a) Place a prism on a white sheet of paper with the triangular face on the sheet and trace its boundary ABC. (i) Fix two pins T and S on one side. (ii) Place the prism on the boundary ABC. (iii) Looking through the other side fix two more pins Q and R in such a way that the all four pins appear to be in the same line. (iv) Remove the pins and mark their positions. (v) Join TS and RQ and extend them to meet the faces of the prism at P and O respectively. (vi) Join PO. (vii) TP represents the incident ray. (viii) PO represents the refracted ray. (ix) And OR represents the emergent ray which is bent towards the base. (x) Let PN and ON be the normal at the points P and O respectively. (xi) And let i be the angle of incidence and r the angle of refraction. (xii) If the incident ray TP is extended forward and the emergent ray RO backwards, they meet at M, forming the angle OML. (xiii) Measure the angle OML. (xiv) This angle is CALLED the angle of DEVIATION. (xv) Angle of deviation is the angle through which an incident ray deviates. (xvi) Repeat this for different values of angle of incidence.  `{:("PE - Incident ray",anglei-"Angle of incidence"),("EF - Refracted ray",angler-"Angle of refraction"),("FS - Emergent ray",angle e-"Angle of emergence"),(angleA-"Angle of the prism",angleD-"Angle of deviation"):}` (b) Rainbow FORMS when sunlight hits the water droplets suspended in the atmosphere and UNDERGOES total internal reflection. When the sunlight comes out of the drop it disperses, where the drop acts like a small prism. This dispersion or breaking up of light into several colours forms the Rainbow. 
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| 711. |
Primary of a transformer has 20,000 turns and the secondary has 30,000 turns. 160V AC is applied at the primary ofthe transformer? lf the number of turns in the secondary transformer is greater than that in the primary then more voltage is induced in the secondary. Why? |
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Answer» |
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| 712. |
State the types of environment? |
| Answer» SOLUTION :The TWO types of environment are NATURALAND ARTIFICAL environment. | |
| 714. |
If the image formed by a mirror for all positions of the object placed in front of it is alwasys erect and diminished, what type of mirror is it? Draw a ray diagram to justify your answer. Where and why do we generaly usethis type of mirror? |
Answer» SOLUTION :Convex mirror  Use : As rear view mirror in vehicles/ Alsoin Malls, Hotels, Aorports for security reasons. REASON: (i) forms ERECT IMAGE (ii) Winder FIELD to view. |
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| 715. |
If crushed ice is pressed and then the pressure is released, a lump of ice is formed. Why does this happen? Explain with reference to regelation. |
| Answer» Solution :(1) When crushed ice is PRESSED, its melting point is lowered and some ice meltsto FORM water. (2) When pressure is RELEASED , the melting point becomes normal and the water freezes to form ice FORMING a LUMP. | |
| 716. |
All artificial satellites do not revolve in similar ...... ...... around the earth. |
| Answer» Solution :Orbit. Because the FUNCTIONS of the SATELLITE decide the HEIGHT of the satellite 's orbit from the earth's SURFACE, the nature of the orbit ( circular/elliptical) and whether the orbit shall be PARALLEL to equator or making some angle with it. | |
| 717. |
A source and listener are both moving towards each other with a speed v/10 where v is the speed of sound. If the frequency of the note emitted by the source is f, what will be the frequency heard by the listener? |
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Answer» Solution :When SOURCE and listener are both MOVING towards each other, the apparent frequency is `N.=((V+v_(t))/(v-v_(s)))n` `n.=((v+(v)/(10))/(v-(v)/(10)))n` `n.=(11)/(9).F` `=1.22f` |
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| 718. |
State Ohm's Law. Draw a circuitdiagram to verify this law indicating the positive and negative terminals of the battery and the meters. Also show the direction of current in the circuit . |
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Answer» SOLUTION :Ohm.s Law : It states that "Physical conditions remaining same, the current flowing through a conductor is DIRECTLY proportional to the potential DIFFERENCE across its two ends". i.e., `V alpha I` `V = IR ` where the constant of proportionality R is called the electrical resistance or resistance of the conductor. Diagram to Verify Ohm .s Law : 
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| 720. |
Human eye is _____ in nature. |
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Answer» CONVEX |
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| 721. |
Wheneverthere is a relative motion between a magnet and a coil, a currentis inducedin the coil. Name this phenomenon. |
| Answer» SOLUTION :ELECTROMAGNETIC INDUCTION | |
| 722. |
Find out, from Table 10.3, the medium having highest optical density. Also find the medium with lowest optical density. |
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Answer» SOLUTION :HIGHEST optical DENSITY = Diamond LOWEST optical density = AIR Optical density of a medium is directly related with the refractive index of that medium. A medium which has the highest refractive index will have the highest optical density and vice-versa. It can be observed from table 10.3 that diamond and air respectively have the highest and lowest refractive index. Therefore, diamond has the highest optical density and air has the lowest optical density. |
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| 723. |
A boy weighing 350 N climbs up 30 steps.each 20 cm high in 1 minute .Calculte: (i)The work done ,and (ii)the power spent. |
| Answer» SOLUTION : (i) 2100 J, (II)35 W | |
| 724. |
State the rule to determine the direction of a (i) Magnetic field produced around a straight conductior carrying current, (ii) Force experienced by a current carrying. Straight conductor placed in a magnetic field which is perpendicular to it and (iii) Current induced in a coil due to its rotation in a magenetic field |
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Answer» Solution :(i) Maxwells RIGHT hand thumb rule (ii) FLEMINGS left hand rule (iii) Fleming.s right hand rule |
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| 725. |
_________ is defined as the amount of heat energy required to rise the temperature of 1 kilogram of water through 1^(@)C. |
| Answer» SOLUTION :ONE KILOCALORIE | |
| 726. |
What is necessary to convert this picture into food web ? Why ? |
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Answer» Solution :a. For converting the above food chain into food web, more animals or links that MAY be present in the terrestial ecosystem need to be added, e.g., BLUEBIRD , rabbit, rat,deer, tiger,etc. b. It is necessary to include these animals because food web is an intricate network of food CHAINS which are interconnected at variouslevels. c. For instance, if we include rat, it would be a food source for snake as WELL as eagle. Similarly, if we includea bluebird, it would feed on grasshopper and the bluebird is eaten by a hawk. d. Thus, the food chain GETS inter-connected at various levels, forming a intricate web instead of linear chain. |
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| 727. |
A lightrayenteringglassfromwater,_______ |
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Answer» It goesaway FROMTHE NORMAL |
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| 728. |
List two reasons which limit the usage of solar cells for harnessing energy for domestic use. |
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Answer» Solution :(i) Availability of the special grade silicon for making solar CELLS is limited. (II) The PROCESS of manufacturing is expensive. Silver used for interconnections of the cells in the panel further adds to the cost. |
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| 729. |
What is photo -voltaic effect? |
| Answer» SOLUTION :The PROCESS of a solar photo-voltaic cell converting solar radiations ENERGY directly into electrical energy is CALLED photo-voltaic effect. | |
| 730. |
Fuse wire , M.C.B. Rubber gloves, Generator. |
| Answer» Solution :Generator. It converts mechanical ENERGY into ELECTRIC energy. All others are related to safety MEASURES to AVOID mishap due to electricity. | |
| 731. |
A body ,when acted upon by a force of 10 khf , get displaced by 0.5 m.Calculate the work done by the force,when the displacementis (i) in the direction of force ,(ii)at an angle 60^(@) with the force ,and (iii)normal to the force ,(g=10 N kg^(-1)) |
| Answer» SOLUTION :(i) 50J (II) 25 J (III) zero | |
| 732. |
At natural state , all earthly bodiesare in a state of rest or in ____________. |
| Answer» SOLUTION :UNIFORM MOTION | |
| 733. |
State two positions in which a concave mirror produces a magnified image of a given object. List two difference between the two images. |
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Answer» SOLUTION :The two positions are : (i) When an object is placed between the pole (p) and focus (f) of a concave MIRROR, the IMAGE formed is larger than the object (or MAGNIFIED ). (ii) When an object is placed between the focus (f) and centre of concave mirror (c) of a concave mirror , the image formed i larger than the object. Difference between the two IMAGES 
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| 734. |
What are electric generators or dynamos ? What is their principle ? |
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Answer» Solution :Electric Generators or Dynamos. Electric generators are devices used to produce electric current. They convert mechanical energy into electric energy. The direction of the current produced in dynamos is in accordance with Fleming.s right hand rule has ALREADY been DESCRIBED. Principle of Electric Generators. Electric generators are based upon the principle of electromagnetic INDUCTION. When a coil is moved in the MAGNETIC field, then the current is induced in the conductor or the coil. In dynamos, a rectangular coil having straight sides is made to rotate rapidly in the magnetic field between the poles of a horse-shoe magnet. These days, we use electromegnets INSTEAD of permanent magnets. When the coil rotates, it cuts the magnets lines of force due to which a current is produced in dynamo coil. |
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| 735. |
In vacuum all freely falling bodies |
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Answer» have the same speed |
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| 737. |
Explain why only a small part of the solar energy that strikes the upper regions of atomosphere reaches the surface of the Earth. |
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Answer» Solution :When the solar energy falls on the surface of the ATMOSPHERE then the following happens : (i) Some solar energy is reflected back into the following happens: (ii) The atmosphere also absorbs a lot of solar energy , for example, most of the ultraviolet rays are absorbed by the ozone layer. So , the solar energy which REACHES us through the Earth.s atmosphere are mainly in the form of heat rays (INFRA red rays) and visible LIGHT, which is a small part of the solar energy. |
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| 738. |
Cooking gas containers are kept in lorry moving with uniform speed what will be the effect on temperature of gas molecules? |
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Answer» Solution :If the LORRY is MOVING with uniform speed the speed of cooking GAS molecules will also be uniform and the collisions will be least or LOSS of KE will be least in turn increase in temperature will be LESS. If lorry is not moving with uniform the cylinders and molecules collide more and more and their temperature may increase and can cause the fire in gas. |
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| 740. |
An object is kept at a distanceof 5 cm in front of a convex mirror of focal length 10 cm. Calculate the position and nature of the image formed. |
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Answer» SOLUTION :u=-5cm, f=10cm,V=? `1/v+1/u=1/f` or `1/v=1/f-1/u` `1/v=1/10-1/((-5))=3/10` or `v=10/3=3.33cm` Nature of IMAGE Virtual and erect. |
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| 741. |
Give some examples of vibrating bodies which produce sound? |
| Answer» SOLUTION :Drums, TABLA, CALLING BELL, SCHOOL bell etc. | |
| 742. |
The electrical resistivities of four materials A, B, C and D are given below:A : 110 xx 10^(-8) Omega m B : 1.0 xx 10^10 Omega m C : 10.0 xx 10^(-8) Omegam D : 2.3 xx 10^3 Omega m Which material is a (a) good conductor (b) resistor (c) insulator (d) semi-conductor? |
| Answer» SOLUTION :(a)C, (B)A, (c)B, (d)D | |
| 743. |
What is the electromagnet? Draw a circuit diagram to show low a soft iron piece can be transformed into an electromagnet. |
Answer» Solution : The magnetic FIELD produced due to current flowing in a coil or a solenoid can be used to magnetise a material like SOFT iron TEMPORARILY. The insulated copper wire is wrapped on a soft iron piece. When current is PASSED through the coil using a battery and a key the iron piece BEHAVES like a bar magnet as long as current is being passed. Such a magnet is called an electromagnet. |
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| 744. |
Magnetic field lines cannot intersect at any point except the magnetic poles of a magnet. |
| Answer» SOLUTION :MAGNETIC FIELD lines cannot INTERSECT EVEN at the magnetic poles. | |
| 745. |
Two blocks of mass 2 kg and 5 kg are connected by an ideal string passing over a pulley. The block of mass 2 kg is free to slide on a surface inclined at an angle of 30^@ with the horizontal whereas 5 kg block hangs freely. Find the acceleration of the system and the tension in the string. |
Answer» Solution : Let a be the acceleration of the SYSTEM and T be the Tension in the string. Equations of motions for 5 kg and 2 kg blocks are 5g-T=5a .......(1) `T-2g SIN theta-f=2a ........(2)` where f=force of limitating FRICTION `=muR=u mg cos theta=0.3 xx 2g xx cos 30^(@)` Solving (1) & (2), `a=4.87 m//s^(2)` T=24.65 N |
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| 747. |
An athlete runs a certain distance before taking a long jump. Why ? |
| Answer» Solution :So that inertia of motion may HELP him in his muscular efforts to TAKE a longer JUMP. | |
| 748. |
State ohm's law |
| Answer» Solution :Temperature REMAINING CONSTANT, the current passing through a conductor is directly PROPORTIONAL to the potential difference across its ENDS i.e., `V prop I or V=IR` | |
| 749. |
Conductance is the property of the material to oppose the flow of charges |
| Answer» SOLUTION :RESISTANCE is the property of the material to OPPOSE the FLOW of charges. | |
| 750. |
Apparent duration of a day is ______________ than the actual duration of the day . |
| Answer» SOLUTION :4 MINUTES more. | |