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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.
| 401. |
A student obtains a blurred image of an object on a screen by using a concave mirror. In order to obtain a sharp image on the screen, in which direction he will have to shift the mirror? |
| Answer» Solution :He will have to shift the MIRROR towards the SCREEN. This is because the blurred IMAGE of an object is obtain only when the SEPARATION between the screen and mirror is less than focal LENGTH. | |
| 403. |
A body of mass 0.3 kg is taken up an inclined plane to length 10 m and height 5 m and then allowwed to slide down to the bottom again.The coefficient of friction between the body and the plane is 0.15. what is the (i) work done by the gravitational force over the round trip. (ii) work done by the applied force over the upward journey. (iii) work done by frictional force over the round trip. (iv) Kinetic energ of the body at the end of the trip. How is the answer to (iv) related to the first thre answer? |
Answer» Solution : `sin theta=(CB)/(CA)=0.5` `:. theta=30^(@)` (i)`W=FS=-mg sin qxxh=-14.7J` is the W.D. by gravitational force in moving the body up the inclined plane. `W'=FS=+mg sin thetaxxh=14.7J` is the W.D. by gravitationa fore in moving the body down the inclined plane. `:.` Total W.D. round thetrip, `W_(1)=W+W'=0` (ii) Force NEEDED to over the body up the inclined plane `F=mgsin theta+f_(k)` `=mg sin theta+mu_(k)R` `=mg sin theta+mu_(k)mg cos theta` `:.` W.D. by force over the upward journey is `W_(2)=Fxxl=mg(sin theta+mu_(k)cos theta)l` `=18.5J` (iii) W.D. by frictional over the round trip, `W_(3)=-f_(k)(l+l)=-2f_(k)l` `=-2mu_(k)mg cos theta l=-7.6J` (IV) K.E. of the body at the end of round trip `=` W.D by net force in moving the body down the inclined plane `=(mg sin theta-mu_(k) mg cos theta)l` `=10.9J` `implies` K.E. of body `=` net W.D on the body. |
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| 404. |
In addition to the artificial satellite, some other ... .... ..... are also revolving around the earth |
| Answer» Solution :OBJECTS. It includes, non-functional satellites, parts of the launcher DETACHED during launching and DEBRIS generated due to collision of SATELLITE with other satellite or ANYOTHER object in the space. | |
| 405. |
On the basis of the structure of disaster-management authority form the same for your school. |
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Answer» Solution :The recommended structure for a School Disaster Management Committeed (SDMC) is as follows: i. Chairperson: Principal ii. Vice principal, Heads of primary and middle sections iii. Education Office/Deputy Education Officer for the zone iv. PARENT Teacher Association President V. 4 students (NCClt NSS, Scouts and Guides, Head Boy adn Head Girl) vi. Representative of Relief/Revenue/Disaster Management Department /District vii. Representative of the Fire services (from closest fire station) or Civil Defence Personnel viii. Representative of Polic (from closest police station) ix. Representative of Health Department (Local Doctor) x. A warden from Civil Defence Various sub-committees like awareness generation and warning and information dissemination TEAM, evacuation team, search and rescue team, fire satety team, first aid team, bus safety team, site security team, will work under the overall supervision of SDMC. The roles and responsibilities of these committees during disasters as well as peace time need to be defined CLEARLY. |
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| 406. |
A person is unable to see objects nearer than 50 cm. He wants to read a book placed at a distance of 25 cm. Find the nature, focal length and power of the lens he requires for his spectacles. |
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Answer» Solution :This person has defect of Hypermetropia which is far SIGHTEDNESS that means the image is formed beyond the retina so it requires a convergent lens to get focused at retina. Now corrective measure is `V=-50cm` `(1)/(f)=(1)/(v)-(1)/(u)` `(1)/(f)=(1)/(-50)-(1)/(-25)` `=-(1+2)/(50)=(1)/(50)` `f=50cm` `P=(1)/(f)` `P=(100)/(50)=2D` Focal length = 50 CM. Power = 2 D |
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| 407. |
A calorimeter has mass 100 g and specific heat 0.1 kcal/kg ""^@C. It contains 250 g of liquid at 30 ""^@Chaving specific heat of 0.4 kcal/kg ""^@C. If we drop a piece of ice of mass 10 g at 0 ""^@C, what will be the temperature of the mixture? |
Answer»  We know that: Latent HEAT of melting the ice `= L_("melt")` Calculation: Heat gained in converting ice to water at `0^@C, Q_3 =m_("ice")L_("melt")=10xx80 =800 ` cal . Heat gained in raising temperature of water from `0^@ " to " T^@C,` `Q_2 = m_("water")C_("water") Delta T` `=10 xx 1 xx (T-0)= 10 T` Heat lost by liquid cooling from `30^@C"to" T^@C`, `Q_3=m_("liq") C_("liq") Delta T' ` `=250 xx 0.4xx (30 -T) ` Heat lost by calorimeter in cooling from `306@C " to " T^@C` `Q_4 =m_("calorimeter ")C_("calorimeter")Delta T,` `=100 xx 0.1 xx (30-T)=10 xx (30-T)` According to principle of heat exchange, `Q_1 +Q_2=Q_3+Q_4` `therefore 800 + 10T =100(30-T)=10(30-T)` `therefore 800 +10 T =110 (30-T)` `therefore 800 +10 T=3300 -1100 T` `therefore120 T = 300-800=2500` `thereforeT= (2500)/(120) = 20.8 ^@C` |
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| 408. |
Focal length of a lens is + 20 cm. Its power is _________. |
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Answer» <P> |
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| 409. |
You found the relative densities of some solids and some liquids by doin some activities. List the solids and liquids in increasing order of relative density. |
Answer» SOLUTION :
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| 410. |
Name the physical quantities which are indicated by the direction of thumb and forefinger In the Fleming's right hand rule. |
| Answer» SOLUTION :DIRECTION of MOTION of the CONDUCTOR and direction of FIELD . | |
| 411. |
A glass sla made of a material of refractive index n_(1) is kept in a medium of refractive index n_(2). A light ray is incident on the slab. Complete the path of rays of light emerging from theglass slab, if : (i) n_(1)gtn_(2') (ii) n_(1)=n_(2)' (iii) n_(1)ltn_(2) |
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Answer» Solution :(i) When `n_(1)gtn_(2)` Light goes from RARER to denser medium `:.` it diverges.  (II) When `n_(1)=n_(2)` There is no CHANGE in the medium `:.` bending or refraction occurs.  (III) When `n_(1)ltn_(2)` Light goes from denser to rarer medium `:.` It CONVERGES. 
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| 412. |
Thereactionof waterwithslaked limeisstudied by ____ |
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Answer» Puttingslakedlimeintowatertakenin a testtube. |
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| 413. |
What is an electricfuse ? How does it function ? |
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Answer» SOLUTION :An electricfuseisan important component of all domesticcircuits . It is used to avoidincidentssuch as electricshock ,fire, DAMAGE toan electricappliancedue to (a) short - circuitingor (b) overloading(darwing a current beyonda specified limit) in a circuit . A fuseisa mostimportant safety device . Itconsists foshortthintin-placed copperwire havinglow melting point . It meltsandbreaks the circuitif thecurrentexceeds a safevalue . Important pointsregrarding a fuse : (1) A fusein always connected in seires with the live wire . (2) A fuse is alwaysconnectedin thebeginingof the circuit . (3) Thethicker the fusewire,the greateris itscurrent- carrying capacity(also called currentratting) less than the maximumcurrentwhicha circuit (or an appliance ) canwithstand .  Two different typesofelectric fuseused in a domesticcircuit are SHOWN above . Twodifferents TYPES of eletric fuse usedin adomesticcircuitare shown above . The useof an electricfusepreventsa possibledamgeto theelectriccircuit and the applianceby stoppingthe flow of undulyhigh electriccurrent . The joule heatingof the fusemeltsit. Thisbreaksthe electriccircuit . |
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| 414. |
What is hacking of information |
| Answer» Solution :When USING some internet programe,the confidential information about government institutes and companies is procured from theinternet and this data or other IDEAS are MISUSED then it is CALLED hacking of information | |
| 415. |
White revolution : Increase in dairy production : : Green revolvution : …… |
| Answer» SOLUTION :INCREASE in CROP YIELD | |
| 416. |
Name some sources of direct current . |
| Answer» SOLUTION :Some OFTHE sources of direct CURRENT are DYNAMO, batteries, dry CELLS, photovoltaiccells, DC generators, etc. | |
| 417. |
____________helps to improve concentration in the studies |
| Answer» Solution :`UL ( MEDITATION) ` HELPS to improve concentration in the studies. | |
| 418. |
The acceleration of a body projected upwards with a certain velocity is |
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Answer» 9.8 `m/s^(2)` |
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| 419. |
Define one calorie. |
| Answer» Solution :One calorie is DEFINED as the amount of the ENERGY required to RISE the temperature of 1 gram of WATER through `1^(@)C` | |
| 420. |
Can we create a rainbow artificially ? |
| Answer» SOLUTION :YES, we can CREATE a RAINBOW ARTIFICIALLY. | |
| 421. |
The current following through a resistor connected in an electric circuit and the potential difference applied across its ends are shown in the figures below : The value of the resistance of the resistor is : |
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Answer» `10 OMEGA` |
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| 422. |
What type of generator is used at Power Stations ? |
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| 423. |
State and prove the law of conservation of energy. |
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Answer» Solution :There is no change in the linear momentum of system of bodies as long as no net external force acts on them . (ii) Let us prove the LAW of conservation of linear momentum with the following illustration :  (iii) Let two bodies A and B having masses `m_1` and `m_2` move eith initial VELOCITY `u_1` and `u_2` in a straight line. (iv) Let the velocity of the first BODY be higher than that of the second body. i.e `u_1 gt u_2` (v) During an interval of time t second , they tend to have a collision . After the IMPACT, both of them move alon the same straight line with a velocity `v_1` and `v_2` respectively . Force on body B due to A. `F_(B)= (m_2[v_2-u_2])/(t)` Force on body A due to B . `F_(A) = (m_1[v_1 -u_1])/(t)` By Newton .s III law of motion , Action force = Reaction force `F_(A) = - F_(B)` `(m_1[v_1-u_1])/(t)=- (m_2[v_2-u_2])/(t)` `m_1 v_1 -m_2v_2 + m_2 mu_2` `m_1v_1 + m_2v_2 = m_1u_1 + m_2u_2` The above equation confirms in the absence of an external force, the algerbraic sum of the momentum after collision is numerically equal of the algebraic sum of the momentum beforce collision . Hence of the law of conservation linear momentum is proved . |
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| 424. |
Intext Question. Take two convex lenses of different sizes. Collect sunlight on a paper using one of the lenses. The paper will start burning after a while. Note the time required for the paper to start burning. Repeat the process for the second lens. Is the time required the same in both cases? What can you tell from this? |
| Answer» Solution :No. Both the lenses will take different time to BUM the PAPER. We can CONCLUDE that the capacity of a lens to CONVERGE the incident light is different for different lens and it depends on the SIZE of the lens. | |
| 425. |
Silver gets correded due to ………………. In air . |
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Answer» OXYGEN |
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| 426. |
Resistivity of pure metals is more than alloys. |
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Answer» SOLUTION :FALSE. Resistivity of PURE METALS is LESS than that of alloys. |
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| 427. |
A block A, weighing 100 N is pulled up a slope of length 5 m by means of a constant force F (= 100 N) as illustrated in Fig. (a) What is the work done by the force F in moving the block A 5 m along the slope ? (b) What is the increase in potential energy of the block A? (c) Account for the difference in the work done by the force and the increase in potential energy of the block |
| Answer» Solution :(a) 500 J (b) 300 J (C) The difference 1.c, 200 energy is used in doing WORK against the FORCE of friction between the block and the slope which will appear as HEAL energy | |
| 428. |
Which uses more energy, a 250W TV set in 1 h, or a 1200W toaster in 10 minutes? |
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Answer» SOLUTION :For TV set: Power P = 250 W = `250J/s` TIME t = 1 h = 3600 s Electric energy (USED by TV set) `= P xxt ` `= 250 J/sxx3600 s` `= 900000 =900 kJ` For toaster : Power P = 1200 W = `1200 J/s` Time t = 10 minture `=10 xx 60 = 600s` Electric energy (used by toaster) `= P xx t` `=1200 J/sxx 600s = 720000 =720kJ` From above calculations, it is clear that a 250W TV set in 1 h consumes more electric energy than a 1200 W toaster in 10 minute. |
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| 429. |
What are environmental Problems ? |
Answer» SOLUTION :
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| 430. |
Given that int (dx)/(sqrt(2 ax - x^2)) = a^n sin^(-1) ((x-a)/(a)) where a is a constant. Using dimensional analysis. The value of n is |
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Answer» 1 No DIMENSION`1 = a^(n)`Possible for`n = 0` |
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| 431. |
Make a diagram to show how hypermetropia is corrected. The near point of a hypermetropic eye is 1 m. What is the power of the lens required to correct this defect? Assume that the near point of the normal eye is 25. cm. |
Answer» Solution :Aperson suffering from hypermetropia can see DISTINCT objects clearly but faces difficulty in seeing nearby objects clearly. It happens because the EYE lens focuses the incoming divergent - rays beyond the retina. This defect of vision is corrected by USING a convex lens. A convex lens of suitable power converge the incoming light insuch a way that the image is formed on the retina, as shown m the following figure.  The convex lens actually ereates a virtual image of a nearby object (N. in the figure) at the NEAR point of visiori (N) of the person suffering from hypermetropia. The given person will be able to clearly see the object kept at 25 cm ( near point of the normal ·eye), if the image of the object is fmmed at his. near point, which is given as 1 m. Object DISTANCE, u=-25 cm Image distance, v=-1m=-100m Focal length f using the formula, `1/v-1/u=1/f` `-1/(100)-1/(-25)=1/f` `1/f=-1/(25)-1/(100)` `1/f=(4-1)/(100)` `f=(100)/3=33.3cm=0.33m` we know, Power, `P=1/(f("in metres"))` `P=1/(0.33)=+3.0D` A convex lens of power +3.0 D is required to correct the defect. |
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| 433. |
Two circular coils A and B are place close to each other . If the current in the coil A is changed, is somecurrent inducedin the coil B ? Give reason. |
| Answer» Solution :YES, if current is changed in coil A, current is induced in coil B. When the CURRENTIN coil A is changed, the MAGNETIC field around it also changes. As the coil B is PLACED very close to thecoil A, the magnetic field lines aroundcoil B also CHANGE and so, currentis induced in it. | |
| 434. |
Powered CaCO_(3)reacts morerapiddlythanflaky CaCO_(3) because of _____. |
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Answer» LARGE SURFACE area |
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| 435. |
Fairy decorative lights are always connected in parallel. |
| Answer» Solution :If the FAIRY lights are connected in series, the equivalent resistance offered will be GREATER and the BRIGHTNESS of the bulbs will be affected. But in parallel connection all the bulbs will GLOW with same intensity and if anyone bulb gets fused the other bulbs will CONTINUE to glow. | |
| 436. |
A concave lens of focal length 15cm forms an image 10cm from the lens. How far is the object placed from the lens? Draw the ray diagram. |
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Answer» Solution :Focal LENGTH of concave lens `(OF_1)`,f=-15cm Image distance, `v=-10cm` ACCORDING to the lens FORMULA, `1/v-1/u=1/f` `1/u=1/v-1/f` `=(-1)/(10)-1/(-15)=(-1)/(10)+1/(15)=(-5)/(150)` u=-30cm |
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| 437. |
Why do stars appears to twinkle? Explain. |
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Answer» Solution :Stars are very distant and approximate point-sized sources. Path of star LIGHT CHANGES continuously due to gradual CHANGING of refractive index of the layers of air. Thus, the apparent position of the stars fluctuates and the amount of starlight entering the EYE flickers GIVING the twinkling effect. |
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| 438. |
An electric motor converts |
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Answer» MECHANICAL ENERGY into electrical energy. |
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| 439. |
Two electric lamps are rated as 220V,100W and 220V, 40W respectively. Their electric resistances are |
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Answer» `484 Omega,1210 Omega` `therefore` ELECTRICAL resistance of 100W lamp `R_1=V^2/P_1=(220 TIMES 220)/100=484 Omega` and electrical resistance of 40W lamp, `R_2=V^2/P_2=(220 times 220)/40=1210 Omega` |
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| 440. |
Draw the diagram showing the structure of schematic sectional view of the human heart and label the following parts . i) arota ii) septum |
Answer» SOLUTION :
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| 441. |
How many resistors of 88 Omega are connected in parallel to carry 10 A current on a 220 V line ? |
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Answer» <P> SOLUTION :Let n number of resistances are connected in parallel.Equivalent resistance `, (1)/(R_(P)) = (n)/(88)` `R_(p) = (88)/(n)` V = IR or R` = (V)/(I)` `(88)/(n) = (220)/(10)` `n = (88) /(22)` = 4 resistors |
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| 442. |
State one limitation of solar energy available from solar cells. |
| Answer» SOLUTION :(a) The EFFICIENCY is very LOW. | |
| 444. |
2Ag_(2)O to 4Ag + O_(2) uarr |
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Answer» Solution :`2Ag_(2)O to 4Ag + O_(2) UARR` In THISREACTION, reduction of ` Ag_(2)O`takes place. |
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| 445. |
How do we decide that a givenmaterial is a good conductor of electricity or is an insulator ? |
| Answer» SOLUTION :Any MATERIAL can be CATEGORISED as a good conductor of ELECTRICITY or an insulator based on its resistance value. Materials having very LOW resistance are good conductors of electricity while materials having very high resistance are insulators. | |
| 446. |
Incomplete combustion of coal and petroleum :(A) increases air pollution.(B) increases efficiency of machines.(C) reduces global warming.(D) produce poisonous gases.The correct option is : |
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Answer» (A) and (B) |
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| 447. |
State the conclusion from the observation that a current-carrying wire deflects a magnetic needle placed near it . |
| Answer» SOLUTION :The conclusion is that a magnetic FIELD exists AROUND a current-carrying CONDUCTOR. | |
| 448. |
" "_(2)n_(1)=(v_(1))/(v_(2)): :""_(1)n_(2): ……………….. |
| Answer» Solution :`(v_(2))/(v_(1))` : Velocity OFLIGHT in a MEDIUM depends on the refractive INDEX of the medium. | |
| 449. |
The gramatomicmassof an elementhasno unit |
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Answer» SOLUTION :(a) True (b) FALSE. Correct statement: The gram ATOMIC mass of an element is EXPRESSED in the unit .grams.. |
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| 450. |
A convex mirror of focal length f produces animage (1/n)^(th) of the size of the object. Then the distance of the object from the mirror is |
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Answer» nf `THEREFORE v=u/n` We have, `1/v+1/u=1/(f)` `therefore n/u - 1/u =1/f` or u=(n-1)f |
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