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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.
| 3351. |
Explain why, filament type electric bulbs are not power efficient. |
| Answer» Solution :In FILAMENT type ELECTRIC bulb, we get light when the filament heats up and begins to glow. A LARGE amount of electrical ENERGY is lost as heat. So, this KIND of bulb is energy efficient or power efficient. | |
| 3352. |
Define magnetic field of bar magnet. |
| Answer» Solution : MAGNETIC field AROUND the bar magnt!l is Ute region in which magnetic force DUE to bar magnet can be EXPERIENCED. | |
| 3353. |
The power delivered by a battery of emf, 10 is 10W. Find the current delivered by the battery. |
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Answer» <P> SOLUTION :1 amp`[becauseP=10W,V=10VrArrP-VIrArrI=(P)/(V)=(10)/(10)=1ampl` |
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| 3354. |
One solar panel produces a potential difference of 18 V and current of 3A. Describe how you can obtain a potential difference of 72 Volts and current of 9A with a solar array using solar panels. You can use sign of a battery for a solar panel. |
Answer» Solution :Given potential DIFFERENCE is 18 V and current is 13A. The requirement is potential difference of 72 V and current is 9A Voltage remains the same if CONNECTED in parallel and gets ADDED it they are connected in SERIES. Current remains the same if connected in series but adds if connected in parallel. 
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| 3355. |
Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of magnetic field ? |
Answer» Solution :An ELECTRON beam moving horizontally from back wall towards the front wall is equivalent to a current flowing in the opposite DIRECTION (i.e., from front wall towards the back wall). The deflection of electron beam as SEEN by theobserveris tohis rightside and is shown in Fig. 13.6 . On applyingFleming.sleft - handrule we find thatthe magenticfieldis actingin vertically DOWNWARD direction. 
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| 3356. |
Give the names of two energy sources that you would consider to be exhaustible. Give reasons for your choices. |
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Answer» Solution :(i) FOSSIL FUELS (II) Nuclear fuels Fossil fuels are present in a limited amount in the Earth . Onceexhausted, they will not be available to us again. It takes MILLIONS of years for fossil fuel to be formed. The nuclear materials which can be conveniently extracted from the Earth are limited and hence, they will get exhausted ONE day. |
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| 3358. |
Simple microscope is used for watch repairs. |
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Answer» Solution :i. A magnification of about 20 times is obtained by simple microscope. ii. When an object is placed within the focal length of convex lens, one gets a magnified and erect image of the object. III. Thus, the WATCH repairer can see the minute PARTS of the watch more clearly with the help of simple microscope than the naked eye, WITHOUT any strain on the eye. Hence, simple microscope is USED for watch repairs. |
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| 3359. |
The positions of four elements A, B, C and D in the Modern Periodic Table are shown below. Which element is most likely to form an acidic oxide ? |
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Answer» A |
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| 3360. |
An ammeter has 20 divisions between mark 0 and mark 2 on its scale. Find the least count of the ammeter. |
| Answer» SOLUTION :Least COUNT = `("Range")/("TOTAL NUMBER of divisions")=(2-0)/(20)=0.1A.` | |
| 3361. |
Explain why steel is preferred to copper, braass, aluminium in heavy-duty machines and in structural designs. |
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Answer» Solution :For metals young.s moduli are large. There- fore , these materials require a large force to produce small change in length. To incre- ase the length of a thin steel wire of `0.1cm^(2)` cross-sectional area by `0.1%,` a force of 2000 N is requred. The force required to produce the same strain in aluminium, BRASS and copper-wire having the same cross-sectio- nal area are 690 N, 900N and 1100 N respe- ctively, Itd means that steel is more ELASTIC than copper, brass and aluminium. It is for this REASON that steel is PREFERRED in heavy duty machines and in structural designs. |
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| 3362. |
What is the principle upon which electric motor is based ? |
| Answer» SOLUTION :It is based UPON Fleming.s left HAND RULE. | |
| 3363. |
Complete the chart : Fill up the blank boxes and display the complete chart in classrrom |
Answer» SOLUTION :
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| 3364. |
If the speed of light in a mediumis 1.5xx 10^(8) m/s, what is the absolute refractive index of the medium? |
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Answer» Solution :Given : Velocity of light in vacuum `(v_(1))=3xx10^(8)` m/s Velocity of light in medium `(v_(2))=1.5xx10^(8)` m/s To FIND : Absolute refractive index (n) FORMULA : Absolute refractive index = `("Velocity of light in vacuum")/("Velocity of light in medium")` Solution : Absolute refractive index (n) `("Velocity of light in vacuum"(v_(1)))/("Velocity of light in medium"(v_(2))` `therefore n =(3xx10^(8))/(1.5xx10^(8))` |
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| 3365. |
A cylindrical lens is required to correct |
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Answer» Myopia |
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| 3367. |
Presbyopia, Retina, Nearsightedness, Far-sightedness. Find the Odd one out. |
Answer» SOLUTION :
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| 3368. |
All vertebrates arechordates but all chordatesbut allchordates are not vertebrates. |
| Answer» Solution :(1) All CHORDATES POSSESS notochord in some period of theirdevelopment. (2) All vertebrates also have notochord during embryonic life, which is later REPLACED by vertebral column. (3) THEREFORE all vertebrates are chordates. (4)But some chrodates like Urochordataand cephalochordata do not possess vertebral columnand hencethey are not vertebrates. | |
| 3369. |
Short circuit occurs, when more appliances work together in a circuit. |
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Answer» Solution :False. OVERLOADING OCCURS, when more appliances WORK together in a CIRCUIT. |
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| 3370. |
For domestic purposes, different electrical devices are connected in parallel instead of connecting them in series. |
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Answer» Solution : Each device gets the full and same VOLTAGE as. that of the electricsupply. Also each device gets proper CURRENT DEPENDING on its RESISTANCE. If one of the devices is switched OFF/ON, other electrical devices remain UNAFFECTED. |
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| 3371. |
Rustingof anironnailis a_______ reaction |
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Answer» COMBINATION |
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| 3372. |
Two bodies have their moment of inertia I and 2I respectively about their axis of rotation. If their kinetic energies of rotation are equal, their angular momentum will be in the ratio |
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Answer» `1:2` `1/2I_(1)omega_(1)^(2) =1/2I_(2)omega_(2)^(2) rArr omega_(2) = omega_(1)/sqrt(2)` `L_(1)/L_(2) =1/sqrt(2)` |
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| 3373. |
Three resistances of 2 Omega, 3 Omega and 6 Omega are first connected in series and the equivalent resistance is found to be……… Then the three resistances are connected in parallel Now its equivalent resistance is……… |
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Answer» SOLUTION :`11 OMEGA, 1 Omega` In SERIES `R_s=2+3+6=11 Omega` In parallel `1/R_p=1/2+1/3+1/6=1/1 implies R_p=1 Omega` |
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| 3374. |
When do you see a rainbow in the sky ? |
| Answer» SOLUTION :Due to the REFRACTION, reflection and DISPERSION of sunlight, when the sunlight PASSES through the rain DROPS, we can see the rainbow in the sky. | |
| 3375. |
A source producing a sound of frequency 500 Hz is moving towards is listener with a velocity of 30 ms^(-1). The speed of the sound is 330ms^(-1). What will be the frequency heard by listener? |
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Answer» Solution :When the source is moving towards the stationary listener, the EXPRESSION for APPARENT frequency is `N.=((v)/(v-v_(s)))n` `=((330)/(330-30))xx500` `=550Hz` |
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| 3376. |
The refractive index of glass is 1.5. What is meant by this statement ? |
| Answer» Solution :When we SAY that refractive index of glass is 1.5, we mean that speed of light in glass `v = (C)/(n) = (3 xx 10^(8))/(1.5) ms^(-1) = 2 xx 10^(8) ms^(-1)`. | |
| 3377. |
Haveyou seen a mirage which is an illusion of the appearance of water on a hot road or in a desert ? |
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Answer» Solution :1. Local atmospheric conditions affect the REFRACTION on light. 2. The air near the hot road or desertsurface is hot and hence, rarer than the air above it. 3. Hence, the direction of light rays coming from a distanc,KEEPS changing according to the laws of refraction. 4. The light rays coming frome a distant object appear to be coming from the image of the object inside the ground. This is called a mairage, which can be seen as an illusion of the appearance of water on a hot road or in a desert. |
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| 3378. |
A concave mirror of focal length f can form a magnified erect as well as an inverted image of an object placed in front of it. Justify this statement starting the position of the object with respect to the mirror in each case for obtaining these images. |
Answer» Solution :  IMAGE FORMED by a concave mirror with object PLACED at F  Image formed by a concave mirror with object placed between F and C. |
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| 3379. |
State-the law of volume. |
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Answer» SOLUTION :When the pressure of gas is kept CONSTANT, the volume of a gas is DIRECTLY proportional to the temperature of the gas. `i.e., prop (1)/(V)` (or) `(V)/(T)`= constant |
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| 3380. |
a) State and explain the laws of refraction of light with the help of a labelled diagram. b) What is meant by the refractive index of a substance? c) Light travels through air at 300 million ms^(-1). On entering water it slows down to 225 million ms^(-1). Calculate the refractive index of water. |
| Answer» SOLUTION :`1.24 xx 10^(8)ms^(-1)` | |
| 3381. |
A boy is siting on a merry-go-round which is moving with a constant speed of 10 ms^(-1) . The means that the boy is : |
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Answer» at rest |
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| 3382. |
What is biogas ? Describe the working of a biogas plant with the help of a labelled diagram. |
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Answer» Solution :BIOGAS is a mixture of methane, carbon dioxide , hydrogen and hydrogensulphide . The majar constinuent of biogas is methane. Biogas is produced by the anaerobic degradation of anaerobic degradation of animal wastes like cow - dung or plant wastes in the presence of water. The biogas plant has a DOME - like structure built with bricks. A slurry of cow - dung and water is made in the mixing tank from where it is fed into the digester is a sealed chamber in which there is no oxygen . Anaerobic micro - ORGANISMS that do not require oxygen decompose or break down complex compounds of the cow - dung . It takes a few days for the decomposition PROCESS to be complete and generate gases. The biogas is stored in the gas tank above the digester from which they are drawn through pipes for use. 
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| 3383. |
Give three examples of diseases endangering the social health. |
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Answer» SOLUTION :i. AIDS II. T.B. III. LEPROSY |
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| 3384. |
Why are carbon brushes used ? How do these work? In order to find answers to such questions, visit a nearby workshop and try to understand the construction of an electric motor. |
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Answer» SOLUTION :i. Carbon BRUSHES are USED to press the split RINGS. ii. The contact between the spilt rings and brushes results in the flow of current through the circuit. |
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| 3385. |
The defect of vision which occurs due to excessive curvature of the eye lens is |
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Answer» MYOPIA |
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| 3386. |
Assertion: The effective resistance in a parallel combination is less than the series. Reason: The potential difference across each resistance is same. |
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Answer» if both the assertion and the REASON are trueand the reason is the correct EXPLANATION of the assertion. |
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| 3387. |
Why a leaf must be destarched before starting the experiment showing that light is necessary for photosynthesis ? |
| Answer» SOLUTION :A leaf is destarched so that the previously formed STARCH of the LEAVES goes down into the stem and roots of the plant, so that newly formed starch is only USED used in the experiment. | |
| 3388. |
Resistors with resistances 5 Omega, 10 Omega and 15 Omega are connected in parallel to each other. What will bc thc equivalent resistance of the circuit? |
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Answer» LESS than 5 `Omega` |
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| 3389. |
Explain the underlying principle and working of direct current generator (or DC dynamo) by drawing a labelled diagram. |
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Answer» Solution :A DEVICE used to convert mechanical energy into electrical energy is called an electric generator. An armature-coil ROTATING in a magnetic field develops an alternating emf and sends alternating current in an external circuit. If, however, the connections of the ends of the coil to the external circuit are interchanged every time theemf in the coil reverses, the current in the external circuit flows always in the same direction. This is the principle of a DC dynamo. The working of a single-coil DC dynamo is shown in the figure. The ends of the armature-coil ABCD are connectedto the two separarted segments `R_(1)` of a single copper ring R, which is called the .split-ring commutator.. `R_(1) and R_(2)`rotate along with the armature between two brushes `B_(1) and B_(2)` to which the external circuit is connected. When the armature-coil ABCD is rotated clockwise (say), an emf is induced in the coil and a current flows in the direction ABCD (Fleming.s right-hand rule), as shown in Fig(a). In the external circuit, the current flows from `B_(1)` to `B_(2)`. For half the REVOLUTION, `R_(1)` is in CONTACT with `B_(1) and R_(2)` with `B_(2)`. But as soon as the coil passes the VERTICAL, `R_(1)` comes in contact with `B_(2) and R_(2)` with `B_(1)` and remain so during the next half revolution [Fig. (b)]. Although the induced emf in the coil is reversed and the current in the coil flows in the direction DCBA, but in teh external circuit the current still flows from `B_(1)` to `B_(2)`.  The current generated by such a simple dynamo is uni-directional. As long as the coil is rotating, the direct current flows through the deviceconnected to the terminals of the generator. |
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| 3390. |
Thermal energy always flows from a system at higher temperature to a system at lower temperature |
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Answer» |
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| 3391. |
Why are the rings of cartilages found in trachea of rabbit? |
| Answer» Solution :Tracheal walls AREC supporctecdby rings of cartilage which help in the free PASSAGE of AIR | |
| 3392. |
A body of mass 200 kg is at rest on the earth's surface. (i) Find its gravitational potential energy . (ii) Find the kinetic energy to be provided to the body to make it free from the gravitational influence of the earth. (g = 9.8 m//s^(2) , R = 6400 km) |
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Answer» Solution :Data : m = 200 kg , g= 9.8 m`//s^(2) , R = 6400 km=6.4 xx 10^(6) m` (i) The gravitational potential of the body `- ( GMm)/R = - MGR ( therefore g = (GM)/R^(2))` ` = - 200 kg xx 9.8 m//s^(2) xx 6.4 xx 10^(6) m= - 1.2544 xx 10^(10) J` (ii) To make the body free from the gravitational influence of the earth , it should be PROVIDED KINETIC ENERGY equal to ` 1.2544 xx 10^(10)` J |
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| 3393. |
When white light pass through transparent medium, it is split into colours is called dispersion. |
| Answer» SOLUTION :DISPERSION of LIGHT | |
| 3394. |
The diagram alongside shows an arrangement of three pulleys A,B and C. the load is marked as L and the effort as E. (a) Name the pulleys A,B and C. (b) Mark in the diagram the directions of load (L), effort (E) and tension T_1 and T_(2) in the two strings. (c) How are the magnitudes of L and E related to the tension T_(1) ? (d) Calculate mechanical advantage and velocity ratio of the arrangement. (e) What assumptions have you made in parts (c) and (d) ? |
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Answer» (c) L=4`T_(1),E=T_(1),` (d) M.A.=4, V.R.=4 (e) The pulleys A and B are WEIGHTLESS and there is no friction. |
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| 3395. |
Explain with diagram step-by-step energy conversion inNuclear power plant |
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Answer» Solution :In a nuclear power plant, uranium or plutonium are used as FUEL. B. Conversion of nuclear energy to THERMAL energy during nuclear fission PROCESS :During the fission of nuclei of atoms like uranium or plutonium, the nuclear energy is converted to thermal energy. c.Conversion of thermal energy to kinetic energy in stean:This thermal energy is used to heat the water present in a boiler . Steam of very high temperature and pressure is generated and directed on the blandes of the turbine . d.Conversion of kinetic energy in steam to kinetic energyin turbine:The kinetic energy produced in thesteam is then used to drive the turbine. e Conversion of kinetic energy in turbine toelectrical energy:The turbine rotates the generator connected to it which in turn PRODUCES electrical energy. 
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| 3397. |
Estimate the total number of molecules inclusive of oxygen, nitrogen, water vapour and other constituents in a room of capacity 25.0m^(3) at a temperature of 27^(@)C and 1 atmospheric pressure. |
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Answer» Solution :As Boltzmann's constant `k_(B)=(R )/(N)`, `:. R=k_(B)N` Now `PV=nRT=nk_(B)NT` `:.` The number of molecules in the ROOM `=nN=(PV)/(Tk_(B))` `=(1.013xx10^(5)xx25.0)/(300xx1.38xx10^(-23))` `=6.117xx10^(26)` |
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| 3398. |
Space missions are useful for only knowing about solar system. |
| Answer» Solution :False - Space missions are also useful in learning about earth and earth's weather.It is also useful in contacting with a PERSON in any PART of the WORLD within a SECOND. | |
| 3400. |
What is meant by sustainable management. The environmentalists are insisting upon substainable natural resource management. State its four advantages. |
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Answer» SOLUTION :SUSTAINABLE management is the management of natural resource which requires a LONG term perspective so that they last for generations to come and are not to be exploited by the short term gains. It .s four advantages are as FOLLOWS: • Resources last for a longer duration. • It provides steady ECONOMIC growth • It help in ecological conservation • It reduces pollution. |
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