Saved Bookmarks
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.
| 5951. |
The focal length of the concave lens is 7 m. Calculate the power of lens. |
|
Answer» SOLUTION :Given `F = -7 m` Power of lens = `1/f = 1/(-7)` `= -0.14 "DIOPTRE or" - 0.14 D`. |
|
| 5952. |
During its passage from one medium to another, where does a light ray change its path ? |
| Answer» Solution :At the BOUNDARY FACE SEPARATING the TWO media. | |
| 5953. |
Why are coils of electric toasters and electric irons made of an alloy rather than pure metals ? |
| Answer» SOLUTION :The material of the coil should have high RESISTIVITY as WELL as should have high melting point. Alloys have HIGHER resistivity and melting point in PURE metals. Hence coil of an alloy (nichrome) is used. | |
| 5954. |
Importance of medicinal plants. |
|
Answer» Solution :(1) In Ayurveda practices, the natural remedies were used. Since India had great biodiversity and traditional knowledge of herbal MEDICINAL uses, therefore, people depended on such medicinal plants. (2) In olden days, such herbs were collected by ROAMING in the jungles. (3) Such important medicinal herbs are now cultivated with care. (4) In entire world people have understood the importance of holy basil (tulsi), Adulsa, Jyesthmadh, etc. (5) In some of the allopathy MEDICINES too, the plant extracts are used. (6) Medicines made from harmful chemical have ide effects and are not safe to be used unless there is medical supervision. Therefore, world-wide herbal remedies are gaining more popularity. |
|
| 5956. |
Electric current, if very weak, doesnot produce magnetic field. |
|
Answer» Solution :FALSE. Electric currenty produces MAGNETIC FIELD even if the CURRENT is very weak. |
|
| 5957. |
The time taken by a radiowavw to go and come back after reflection from a communication satellite is |
|
Answer» `(1)/(4)`s `=(72)/(300)=((1)/(4))s` |
|
| 5958. |
u, v, f and r represents the object distance, image distance, focal length and radius of curvature of a mirror respectively. Which of these relations is correct ? |
|
Answer» `r/2=(UV)/(u+v)` |
|
| 5959. |
Draw a labelled diagram of an electric motor. Explain its principle and working . What is the function of a splitring in an electric motor? |
|
Answer» Solution :An electric motor is an electrical device that converts electrical energy into mechanical energy which can be USED to do work. Principle : A current CARRYING conductorplaced in a magneticfield experiencesa force whose direction is given by Fleming.sleft-hand rule. Construction : An electric motor consists of a rectangular coil ABCD of insulated copper wire placed between the two poles of a permanent magnet. The two ends of the coil areconnected to two halves of a split ring P and Qmounted on an axle O. The inner sides of the split ring areinsulated while their outer sides are conducting. The outersides of the split ring are connected to a circuit consisting of a battery and a plug key through two brushes X and Y whose position is fixed. Working : When current is applied, it flows along ABCD . Thus, ACCORDING to Fleming.s left-hand rule, arm AB experiences an upward force while arm CD experiences a downward force. These two equal and opposite forces constitute a couple and cause the coil to rotate in anti-clockwise direction. At half rotation, position of AB and CDis reversedand hencecurrentflowsalong DCBA. Now, CD will experiencean upward force and AB a downwardforce. Thiscauses the coil and the axle to rotate half a TURN more. At each half rotation, the current reverses causing continuousrotation of the coiland the axle . The functionof split rings is to provide unidirectionalcurrent. 
|
|
| 5960. |
Solar energy is a renewable energy. How? |
|
Answer» Solution :(i)Solar ENERGY is renewable, free source of energy, that is sustainable and totally inexhaustible (ii)The circulation in Leech is Haemocoelic system. There are no true blood vessels. The blood vessels are replaced by channels called Haemocoelic channels or canals filled with blood LIKE fluid. The coelomic fluid contain Haemoglobin. There are four LONGITUDINAL channels. One channel lies above (dorsal) to the Alimentary CANAL, one below (ventral) to the Alimentary canal. The other two channels lie on either (lateral) side of the Alimentary canal, which serves as a heart and have inner valves. All the four channels are connected TOGETHER posteriorly in the 26th segment.Thus the circulatory system is designed in Leechto compensate the heart structure . |
|
| 5961. |
A student places a candle flame at a distance of about 60 cm from a convex lens of focal length 10 cm and focuses the umage of the flame on a screen. After that he gradually moves the flame towards the lens and each time focuses the image on the screen. (a) In which direction-toward or away from the lens, does he move the screen to focus the image ? (b) How does the size of the image change ? (c) How does the intensity of the image change as the flame moves towards the lens ? (d) Approximately for what distance between the flame and the lens, the image formed on the screen is inverted and of the same size ? |
|
Answer» SOLUTION :(a) He will move the screen AWAY from the LENS to focus the image. (B) Size of the image GOES on increasing. (c) Intensity of image goes on decreasing. (d) About 20 cms. |
|
| 5962. |
Two wires of equal length, one of copper and the other of manganin have the same resistance. Which wire is thicker ? |
|
Answer» Solution :`R_("copper")= rho_(C) (1_(c))/(A_(c))` `R_(m)= rho_(m)(l_(m))/(A_(m))` Now `"" R_(c) = R_(m) ` ( GIVEN ) `l_(c)=l_(m) ` (given ) `:. (rho_(m))/(A_(c))=(rho_(m))/(A_(m))` or `"" (rho_(c))/(rho_(m))=(A_(c))/(A_(m))` Since `"" rho_(m) lt rho_(c)` `:. "" A_(m) lt A_(c)` Copper wire will be thicker . |
|
| 5963. |
Which ofthe following social determinant make the life secure and safe for women? |
|
Answer» EDUCATION |
|
| 5964. |
The direction of force on a current carrying conductor in a magnetic field is given by |
|
Answer» Fleming's left HAND rule |
|
| 5965. |
What is criticality of a nuclear reaction? How is it achieved? |
|
Answer» SOLUTION :Criticality of a nuclear reaction means that the fissilon PROCESS is so controlled that a manageable constant power output is obtained. It can be DONE In two ways. (i) Use of moderators: The commonly used moderator In the nuclear reactor is graphite. When the high-speed neutrons COLLIDE with the moderator, they lose some of thelr kinetic energy and slow down. lt is compulsory to slow down the speed ot neutrons produced because fast-moving neutrons cannot cause fission of U-235 effectively. (ii) Useof neutron absorber: For energy fission, three neutrons are emitted. So, it Is necessary that extra neutrons are removed. For this, cadmium rods play an important ROLE. These are inserted In the nuclear reactor in such a way that only a requisite number of neutrons are available for fission process to proceed in a controlled manner. |
|
| 5966. |
Force between the masses is always ……………………… |
| Answer» SOLUTION :ATTRACTIVE | |
| 5967. |
The imageobtainedwhilefindingthe focallengthof convexlens is_____ |
|
Answer» A REALAND crect |
|
| 5968. |
List the difference between Dicot and Monocot stem. |
Answer» SOLUTION : 
|
|
| 5969. |
What are the advantages of LED TV over the normal TV ? |
|
Answer» Solution :(a) (i) It has brighter picture quality. (ii) It is thinner in SIZE. (iii) It uses less power and consumes very energy. (iv) Its life SPAN is more (v) It is more reliable (b) (i) As there is no filament, there is no loss of energy in the form of heat. It is cooler than the incandescent BULB. (ii) In COMPARISON with the fluorescent light, the LED bulbs have significantly LOW power requirement. (iii) It is not harmful to the encironment. (iv) A wide range of colours is possible here. (v) It is cost - efficient and energy efficient. (vi) Mercury and other toxic materials are not required. |
|
| 5970. |
The position of three elements A, B and C in the Modern periodic table is as follows :Write formula of compound formed between :(i) B and A,(ii) B and C(b) Is any of the three elements a metal ? Give reason to justify your answer. |
|
Answer» SOLUTION :(i) Between B and A HF (ii) Between B and C `H_2S` (b) None of the three elements is a metal. Although H resembles with elements of Group 1 in some properties but it is not a metal. It exists as a gas and does not SHOW normal properties of metals like electrical and THERMAL conductivity. |
|
| 5971. |
Which are the various ways that help us to relieve stress ? |
|
Answer» Solution :Way to Minimize Stress: (i) Joining a a laughter CLUB. (ii) Communicationwith friends, peers, cousins, expressing and parents, noting down our feelings,expressing our feelings with NEAR nad dear ones HELP us to relieve stress. (iii) Fostering hobbies like meteral colection, photography, reading, cooking, sculpturing, drawin, rangoli, danceing, etc. HELPS to divert energy and mind towards positive energy. (iv) Learning andlistening to music, singing helps to changethe mindset and keepus happy. (v) Regulaar exercvising, massaging, visiting the spa also helps to relive the stress. (vi) Deep breasthing, Yogasanas, Yogic SLEEP, meditation, balanced and good food also help to impart positivity and relieve stress. (vii) Time management, planning of our own dutines and decision power are also effective ways of stress managment. |
|
| 5972. |
Arrange the given media in the increasing order of their optical densities. Water,Diamond,Glass,Air. |
|
Answer» |
|
| 5973. |
What is L.P.G. ? Why is it called a good fuel ? |
|
Answer» Solution :The petroleum gas liquefied under pressure is called liquefied petroleum gas (L.P.G.) It consists mainly of butane with small amounts of propane and ethane. This is the domestic gas that we use. The gas used for domestic cooking PURPOSES is called Liquiefied Petroleum Gas. (L.P.G.) because it is obtained from petroleum and it is liquefied by compression before filling in cylinders. Uses of L.P.G. The L.P.G. is mainly used for domestic heating purposes. It is obtained in cylinders. When we turn the knob of the gas cylinder, the pressure is released resulting in decrease of pressure inside the cylinder so that highly volatile L.P.G. changes into gas. The gasflows to the burner of the cooking STOVE. When ignited, the gas BURNS with a blue flame producing a lot of heat. This heat is used for cooking our food. Advantages of L.P.G. Liquid petroleum gas is CONSIDERED to be a good FUEL because of the following reasons : 1. L.P.G. has a high calorific value. Its calorific value is about 50 kJ/g. This means that when 1 gram of L.P.G. burns in a gas stove, it produces about 50 kJ of heat energy. Therefore, it has higher efficiency as a fuel. 2. It is very neat and clean domestic fuel it burns with a smokeless flame and so does not cause pollution. 3. It does not produce any poisonous gases on burning. 4. L.P.G. is easy to handleand it it convenient to store. 5. It undergoes complete combustion. |
|
| 5974. |
Material : Flexible copper wire, stand,electric cell, a horseshoe magnet with a strong magnetic field.Procedure : Using the stand, fix the copper wire so that it passes through the poles of the horse-shoe magnet as shown in the figure 4.17. Connect the circuit as well. What do you observe? Whenever a current is not flowing through the wire, it remains straight ( position A). When the current flows from top to bottom, the wire bends and comes into position C.If the current direction is reversed, i.e. it flows from the bottom to the top end, the wire bends but comes in the position B. This means the direction of the force on the wire is perpendicular to both the magnetic field and the direction of the current. Here, the direcțion of magnetic field is from N to S, (H). In this experiment it is noted that whenever a current flows through a conductor in the presence of magnetic field, a force is exerted on the conductor. If the direction of the current is réversed, the direction of the force also gets reversed. If the magnet is kept reversed, i.e. its South pole is brought at the position of its North pole and its North pole brought to the position of its South pole, what will happen? |
Answer» SOLUTION : The DIRECTION of the FORCE will be REVERSED. 
|
|
| 5975. |
How many times in one second does an AC with frequency50Hz change its direction? |
|
Answer» 25 |
|
| 5976. |
What happens if a bar magnet is cut into twopieces i] perpendicular to its lengthii] along its length ? |
| Answer» SOLUTION :In both cases, we GET two magnets, each having its own north and SOUTH POLES. | |
| 5977. |
What is the exact difference between grades of organization and symmetry? Explain with examples. |
|
Answer» Solution :I. GRADES of organization : (1) The grades of organization mean the way an organism has different body formation. (2) Unicellular organisms like amoeba have a single cell in the body and hence the organization in its body is called protoplasmic grade of organization. (3) Some organisms have only cells in their body. This is called cellular grade of organization. e.g. Poriferans. (4) Some have tissues e.g. Coelenterates .They are said to have cell- TISSUE grade organization. Some have organs, they are said to have tissue-organ grade e.g. Platyhelminthes. All other higher animals have organ-system grade organization. II. Symmetry : (1) Symmetry on the other hand shows the base of the body formation. (2) The symmetry can be understood by taking an imaginary cut through the animal body. (3) Based on the symmetry there can be three types. (4) In asymmetric animals, there is no symmetry in any plane. e.g. Amoeba. (5) The bilateral symmetry is the one in which an imaginary axis can pass through only one median plane to DIVIDE the body into two equal halves. Most of the animals have bilateral symmetry and hence their organs are arranged in symmetric way on both the sides. (6) The imaginary cut passing through the CENTRAL axis can give more than one equal halves. The organs of such animals are arranged in a radius of an imaginary circle. e.g. Cnidarians and some echinoderms. Both grades of organization and symmetry are the bases for classifying animals into different phyla. |
|
| 5978. |
What is the effect of radiations coming from cell phones ? |
| Answer» SOLUTION :Various physical problems LIKE tiredness, headache, INSOMNIA, forgetfulness, tinnitus, JOINT pains and problems in vision may arise due to radiation of cell phones. | |
| 5979. |
List any four reasons why we need to look for alternate sources of energy. |
|
Answer» Solution :FOUR reasons we NEED to LOOK for alternate sources of energy are: v (i) Pollution due to fossil fuels. (ii) Exhausting fuel reserves. (III) Increasing need. (iv) REPLENISHMENT is not easy. |
|
| 5981. |
You aregiven four ammeters A, B, C and D having the least counts mentioned below : Which of the ammeters would you prefer for doing an experiment to determine the equivalent resistance of two resistance most accurately, when connected in parallel? |
|
Answer» AMMETER A with least count 0.25 A |
|
| 5982. |
How is a normal eye able to see distinctly distant as well as nearer objects? What is the distance of distinct vision? |
|
Answer» Solution :Eye lens is made up of fibrous material. Its curvature can be changed by ciliary muscles which changes its FOCAL length. When muscles are relaxed, the lens becomes thin and focal length increases and the eye is able to see distant objects. Similarly when ciliary muscles CONTRACT, focal length decreases and eye is able to see nearer objects. The minimum distance at which objects can be SEEN distinctly is called distance of DISTINCT vision. It is 25 cm. |
|
| 5983. |
Redraw the circuit of 9.39, putting in an ammeter to measure the current through the resistors and a voltmeter to measure the potential difference across the 12Omega resistor. What would be the readings in the ammeter and the voltmeter ? |
Answer» Solution :The circuit DIAGRAM of above with an ammeter A and a voltmeter Vacross `12Omega` resistor is shown in figure CALCULATION of current flowing in the circuit : Equivalent resistance of the circuit, `R_s = 5Omega + 8 Omega + 12 Omega = 25 Omega` In a series combination, the current flowing through each resistor is the same and equal to the TOTAL current flowing through the circuit. `:.` Current through the resistors, `I + V/R` `= 6/25` `= 0.24 A` Since the current in the circuit and the current through each resistor is the same, the ammeter will show a reading of 0.24 A. Calculation of potential difference across 122 resistor : As total current 0.24 A flows in the circuit, the same current 0.24 A would also flow through the 122 resistor which is connected in series. `:.` The potential difference across the 12 12 resistor, `V = IR` ` = 0.24 xx 12 = 2.88 V` Thus, the p.d. across `12 Omega` resistor is 2.88 volt. So, the voltmeter will show a reading of 2.88 V. |
|
| 5984. |
How can we determine the focal length and power of the convex lens required to correct a hypermetropia eye ? |
Answer» Solution : Let X = distance of the near point N. from the hypermetropic eye. We know that the near point N of the NORMAL eye is at distance D = 25 cm. The object placed at N forms its virtual image at N. due to the convex lens. So, object distance = u = -D,Image distance = v = -x. focal length = f = ? By lens FORMULA, `(1)/(f) = (1)/(v) - (1)/(u) = (1)/(-x)-(1)/(-D) = (x-D)/(xD)` `:.` required focal length, Required Power , `P = (1)/(f) = (x-D)/(xD)` As `x gt D` both f and D are positive. Thus, the correcting lens must be a convex lens. |
|
| 5985. |
What does the degree of closeness of magnetic field lines near the poles signify ? |
| Answer» SOLUTION :Degree of closeness indicates that the relative strength of the magnetic FIELD NEAR the poles where the field lines are crowded is more as COMPARED to other places. | |
| 5986. |
Assertion : During sun set, sun appears red. Reason : Scattering of light is directly proportional to the wavelength. |
|
Answer» Both assertion and REASON are true and reason is CORRECT EXPLANATION of assertion. |
|
| 5987. |
Why do you is the colour of sky blue and not black as in case of themoon? |
| Answer» Solution :Dispersion of LIGHT is inversely PROPORTIONAL to the fourth power of wavelength. Wavelength of blue light is abouthalf of the wavelength of RED light. Hence blue light spreads about 16 TIMES more than red light and hence sky APPEARS blue . | |
| 5988. |
If you see thermal power station, you will observe two types of towers there. What are they? |
|
Answer» Solution :(i) In a thermal power station the two types of tower are : stack is cooling tower. (ii) The stack is a very high tower through which gases that are EMITTED during thecomebustion of coal are RELEASED in the atmosphere. (iii) The cooling tower is USED to store water and to RELEASE vapour and HOT air from the steam in the atmosphere. |
|
| 5989. |
For an invariable mass of perfect gas at constant temperature, product of pressure and volume is ___________. |
| Answer» SOLUTION :PV=constant | |
| 5990. |
A thermally insulated pot has 150 g ice at temperature 0 ""^@C. How much steam of 100 ""^@C has to be mixed to it, so that water of temperature 50 ""^@C will be obtained? (Given: Latent heat of melting of ice 80 cal/g, latent heat of vaporisation of water = 540 cal/g, specific heat of water = 1 cal/g""^@C) |
|
Answer» Change in temperature of water `(DeltaT)` `=50 ""^@C` , We know that: LATENT heat of melting of ice `=L_("melt") = 80 "cal/g"` Specific heat of water `c_w= 1 cal//g^@C` To find : Mass of STEAM (M) flow of heat: Loss of heat: `underset((100""^@C))"steam"overset(Q_1)rarrunderset((100""^@C))"water"overset(Q_2)rarr underset((50^@C))"water"` Gain of water `underset((0^@C))"ice" overset(Q_3)rarr underset((0^2C))"water"overset(Q_3)rarrunderset((50^@C))"water"` Formulai. Heat to be given off in converting steam into at `100^@C (Q_1)=ML_("vap")` ii. Heat to be given off in COOLING water at `100 ^@C`to `50^@C(Q_2)= Mxx C_w xx Delta T` iii.Heat required to convert ice at`0^@C`into water at `0^@ C` intowater `0^@C (Q_3)` `m xx L_("melt")` iv. Heat requiredto reaise temperature of water from `0^@C "to " 50^@C(Q_4)` `m= xx c_w xx Delta T` Calculation: According to princ of heat exchange, `Q_1 +Q_2=Q_3+Q_4` From FORMULAE (i) to(iv), `(Mxx540)+(Mxx1xx50)` `=(150 xx 80 )+(150 xx 1 xx 50)` `M(540+50)=12000 +7500` `therefore590 M = 19500` `therefore M =(19500)/(590) = 33 g ` |
|
| 5991. |
Find the focal length of a convex mirror whose radius of curvature is 30 cm. |
| Answer» Solution :For SPHERICAL mirror, Focal length (f) = `("radius of CURVATURE")/(2) = (30)/(2) = 15 cm ` | |
| 5992. |
In Fig. 1.17 a roller of diameter 0.4m is raised on the pavement XY by forces F_1 and F_2 each of magnitude 10N. Compare the torques produced by the two forces. |
|
Answer» SOLUTION :GIVEN `F_1=F_2=10N` Perpendicular DISTANCE of point of rotation X from the force `F_1` is `d_1=0.4 m` while that of force `F_2` is `d_2=1/2 TIMES 0.4m=0.2m` `("Torque PR oduced by force" F_1)/ ("Torque pr oduced by force" F_2)= (F_1 times d_1)/(F_2 times d_2)` `=(10 N times 0.4 m)/ (10 N times 0.2m )=2/1` |
|
| 5993. |
What is Tyndall effect ? What is its cause? Explain two pheno menon observed in daily life which are based on Tyndall effect. |
|
Answer» Solution :Tyndal cffect: When a beam of light is passed through a colloidal solution placed in a DARK room the path of beam becomes illuminated when observed through a microscope placed perpcndicular to the path of light. This effect is called Tyndall effect. Causes of tyndal effeet: The size of the callidal PARTICAL is relatively larger then the solute particals ofa true solution. The collidal particles first absorb energy from the INCIDENT light and then a PART of energy from their surface. Thus tyndall effect is due to scattering of light by the colloidal particals and the colloidal particles are seen to be moving as points of lights moving aginist a dark background. Daily life examples : (i) When sunlight passcs though a canopy of a dense forest the tiny water droplets in the mist SCATTER light and become visible. (ii) When a fine beam of sunlight entersa smoke filled room through a small hole the smoke particals become visible due to the scattcring of light. |
|
| 5994. |
As we move away from a current carrying conductor, the spacing between the magnetic lines of force............. |
|
Answer» DECREASES |
|
| 5995. |
From the elements Li, K, Mg, C, Al, S identify the most metallic element. |
| Answer» SOLUTION :K is most METALLIC ELEMENT. | |
| 5996. |
Name and explain the type of scattering . |
|
Answer» Solution :Types of Scattering . When a beam of light interacts with a constituent particle of the medium it UNDERGOES many kinds of scattering . Based on initial and final energy of the light beam , scattering can be CLASSIFIED as, Elastic scattering , (ii) Inelastic scattering 1. Elastic scattering If the energy of the INCIDENT beam of light and the scattered beam of light are same , then it is called as elastic scattering. 2. Inelastic scattering If the energy of the incident beam of light and the scattered beam of light are not same , then it is called as inelastic scattering The nature and size of the scatterer results in different types of scattering . They are (i) Rayleigh scattering (ii)Mie scattering (iii) TYNDALL scattering (iv) Raman scattering |
|
| 5997. |
Assertion : Myopia is due to the increase in the converging power of eye lens. Reason : Myopia can be correct with the help of concave lens. |
|
Answer» If both assertion and REASON are true and reason is the CORRECT explanation of assertion. |
|
| 5998. |
How is a voltmeter connected in the circuit to measure the potential difference between two points? |
| Answer» SOLUTION :A voltmeter is (always) CONNECTED in PARALLEL ACROSS the points in the circuit between which the potential DIFFERENCE is to be measured. | |
| 5999. |
Give a brief note on people who have travelled to space. |
|
Answer» Solution :1.The first person to go into the space in a spacecraft was Yuri Gagarin of the then USSR. He orbited the earth in 1961. The first person to step on the Moon ( 1969)was Neil Annstrong of USA. 2. Rakesh Shanna oflndia orbited the earth in 1984 in a RUSSIAN spacecraft. 3. KALPANA Chawla and Sunita Williams of Indian ORIGIN also participated in space EXPLORATIONS through missions organized by NASA (National Aeronautics and Space Administration) of USA. |
|
| 6000. |
In a tug of war between the teams A and B, the rope breaks at a point whch is nearer to A. Then |
|
Answer» A has APPLIED more force |
|