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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.
| 7051. |
Mention why is it not possible to make use of solar cells to meet all our energy needs? State three reasons to support your answer, also mention three uses of solar cell. |
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Answer» SOLUTION :It is not possible to make use of solar cells to meet all our energy needs because, i) Of limited availability of special grade semiconducting materials such as silicon and GERMANIUM ii) Solar cells have lower efficiency as they depend entirely on intensity of solar radiation. iii) The process of manufacturing of solar cells is very expensive, silver used for inter-connection of cells in the panel further add to the cost, Uses of solar cells : i) They PROVIDE electric power to satellites and space probes ii) They provide electric power to off-shore DRILLING plant formed and light houses iii) T.V RELAY stations are wireless transmission systems located in remote areas use solar panels to get electric power |
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| 7052. |
Rajan constructed a small house. He used good qualityand well insulated copper wires for wiring. He also used good quality switches, sockets and plugs. However, had a very old room heater. On one winter night, Rajan was sleeping in a closed room with his family with the room heater switched on. During sleep, Rajan felt suffocated and woke up to see the room heater on fire. Rajan's son Arvind got up quickly and put off the main switch. Arvind also made a telephone call to Fire Brigade. The Fire Brigade men reached quickly and extinguished fire in the room. Rajan and his family thanked the firemen. (a) What was the cause of fire in Rajan's house ? (b) Name the safety device which was missing in the electric wiring of Rajan's house ? (c) How could the above device prevent fire in Rajan's house ? (d) What values are displayed by Arvind in this whole incident ? |
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Answer» Solution :(a) The cause of fire in Rajan's house was short-circuiting (due to the working of an OLD room heater having connecting cord with torn insulation, etc.). (b) ELECTRIC fuse is the safety device which was missing in the wiring of Rajan's house. During short-circuiting, when the live wire and neutral wire touch each other directly, then the resistance of the circuit formed becomes very low due to which too much current passes through fuse wire, the fuse wire gets heated too much, melts and breaks, cutting off the electricity supply in the household circuit. This prevents the electric fire in the house. (d) The values displayed by Arvind in this incident are (i) General awareness (that electric fire can be prevented from spreading by PUTTING off the MAIN switch), and (ii) Presence of mind (in CALLING the Fire Brigade to extinguish fire). |
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| 7053. |
Name the law which helped to find the direction of the magnetic field lines. |
| Answer» SOLUTION :RIGHT hand thumb rule HELPED to find the DIRECTION of MAGNETIC field lines. | |
| 7054. |
State whether the following statements are true of false. An electric motor converts mechanical energy into electrical energy. |
| Answer» SOLUTION :FALSE: An ELECTRIC MOTOR converts electric energy into mechanical energy. | |
| 7055. |
Chief minister is the national disaster management authority. |
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| 7056. |
Can you guess the reason wh the ratio of V and I in case of LED is not constant ? |
| Answer» Solution :This is due to FORWARD voltage and MAXIMUM continuous current RATING characters of LEDS. | |
| 7057. |
Determine the value of the angle of incident for a ray of light travelling from a medium of refractive index mu_(1)=sqrt(2) into the medium of refractive index mu_(2)=1, so that it just grazed along the surface of separation. |
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| 7058. |
If x is the distance at which a car can be stopped when initially it was moving with speed u, then on making the speed of the car Nu, the distance at which the car can be stopped is |
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Answer» Nu |
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| 7060. |
Figure below shows two identical prisms A and B placed with their faces parallel to each other. A ray of light of single colour PQ is incident at the face of the prism A. complete the diagram to show the path of the ray till it emerges out of the prism B. |
| Answer» SOLUTION :The EMERGENT RAY out of the prism B will be PARALLEL to the incident ray PQ | |
| 7061. |
What is meant by electric power? Obtain a formula for it. State units of electric power. |
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Answer» Solution :Power is the rate of doing work. When work is DONE, an equal AMOUNT of electric energy is consumed. Hence, "The rate at which electric energy is consumed or dissipated is called electric power." IF W is the amount of electric energy consumed in a circuit in time t (second), then electric power is given by `P = W/t ......(12.17)` But, the electric energy supplied by a current - source in time t is W =VQ `:.P = (WQ)/t` Now,, current`I +Q/t` `:. P =IV .......(12.18)` FromOhm.s law V = IR So,P = (IR) I `:. P = I^2 R .......(12.19)` Again from the Ohm.s law `I = V/R` So, `P = (V/R)^2R` `:. P = V^2/R` ... ...(12.20) The SI unit of electric power is the watt (W). Hence, from equation (12.18), watt = volt `xx` ampere THUS, 1 W = 1 volt `xx` 1 ampere = 1 VA Definition of the SI unit of power: Electric power consumed by a device is said to be 1 W if it carries 1 A of current when operated at a potential difference of 1 V OR Electric power of an electric device is 1 watt if it consumes 1 joule of electric energy in 1 second. |
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| 7062. |
Name the rule which gives the direction of induced current in a conductor . |
Answer» Solution :Fleming.s right-hand rule is used to find the direction of induced current. This rule states that if thethumb, fore-finger, and middle finger of therighthand are stretched tobe perpendicular to each OTHERAS SHOWN in the FIGURE , and if the thumb represents thedirection of themotion of conductor, fore finger represents direction of the magnetic field, then THEMIDDLE finger represents the direction of theinduced current.
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| 7063. |
Which of the following statement is true ? |
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Answer» <P>A convex lens has 4 D POWER having a FOCAL LENGTH + 0.25 m |
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| 7064. |
Condensation of chromosomes : Prophase : : Formation of spindle fibres : …… |
| Answer» SOLUTION :METAPHASE | |
| 7065. |
Why are tyres made of rubber not of steel ? |
| Answer» Solution :SINCE coefficient of FRICTION between rubber and road is LESS than the coefficient of friction between STEEL and road. | |
| 7066. |
Electrical conductors having higher ............ are used in heating devices. |
| Answer» SOLUTION :RESISTIVITY | |
| 7067. |
A concave mirror has a focal length of 20 cm. At what distance from the mirror should a 4 cm tall object be placed so that it forms an image at a distance of 30 cm from the mirror ? Also calculate the size of the image formed. |
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Answer» Solution :As per question, focal length of CONCAVE MIRROR f = - 20 cm, height of object h = + 4 cm and distance of image v = 30 cm. Following two cases may arise here : Case I : If the image formed is REAL then v = - 30 cm and so from mirror formula `(1)/(v) + (1)/(u) = (1)/(f)`, we have `(1)/(u) = (1)/(f) - (1)/(v) = (1)/((-20)) - (1)/((-30)) = (-1)/(20) + (1)/(30) = - (1)/(60) rArr u = - 60` cm and `h. = - (v)/(u) xx h = - ((-30))/((-60)) xx (+4) = - 2` cm So the object be placed 60 cm in front of mirror and image is an inverted image of size 2 cm. Case II : If the image formed is VIRTUAL then v = + 30 cm and now `(1)/(u) = (1)/(f) - (1)/(v) = (1)/((-20)) - (1)/((+30)) = (-1)/(20) - (1)/(30) = - (1)/(12) rArr u = - 12` cm and `h. = - (v)/(u) xx h = - ((+30))/((-12)) xx (+4) = + 10` cm So the object is placed at 12 cm in front of mirror and image is an erect image of height 10 cm. |
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| 7068. |
Explain the various effects of the disaster of railway accident. |
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Answer» Solution :The VARIOUS effects of rail accident are as follows: i. Economic effect: the destruction of the railway property as well as the expenditure required to restore the same result inhuge economic loss. ii. Social effect: There is los of life. The injured people may not be able to lead a normal life easily thereafter. Also, the destruction of belongings leads to financial loss to the passengers. ii. Environmental effect: Crude oil and other chemicals spilled during accidient from the train can cause soil pollution. If such hazardous chemical get mixed in rivers or streams it can lead to water pollution. ADMINISTRATIVE and management effect: Transport system collapses, the railways are forced to reinstate the system at the earliest which stresses the workers. v. Politial effect: People lose their trust on teh existing government, affecting the ruling political party. vi. HEALTH effect: Injuries, emotional or psychological stress, deaths, ETC. |
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| 7069. |
One mole of an ideal gas at NTP occupies 22.4 liters (molar volume). What is the ratio of molar volume to atomic volume to atomic volume of a mole of hydrogen ? Take size of hydrogen molecule to be 1 Å. Why is this ratio so large? |
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Answer» Solution :`1A^(0)=10^(-10)m` Atomic volume of 1 mole of hydrogen = Avagadros number `×` volume of hydrogen molecule `=6.023xx10^(23)xx(4)/(3)xxpixx(10^(-10)m)^(3)` `=25.2xx10^(-7)m^(3)` Molar volume =`22.4 L = 22.4 × 10^(–3) m^(3)` `("Molar volume")/("Atomic volume")=(22.4xx10^(-3))/(25.2xx10^(7))=0.89xx10^(4)~~10^(4)` This ratio is large because ACTUAL SIZE of gas molecule is negligible in comparison to the inter molecular separation. |
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| 7070. |
In aboveexperiment, whatwillbe themaximumrisein temperatureof wateraftermeltingif ice ? |
| Answer» Answer :D | |
| 7071. |
Draw a labelled ray diagram to show the path of a ray of light incident obliquely on one face of a glass slab. |
Answer» Solution :Path of a LIGHT ray incident OBLIQUELY on ONE face of a glass SLAB is shown below 
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| 7073. |
Draw a ray diagram of formationof images by the convex lens when object placed between1.Infinity, 2. beyond 2F1 |
Answer» Solution :(i)RAY diagram for object placed between F and 2F  (II)`[OH^-]=1xx10^(-11)` m `pOH=-log_10[OH^-]=-log_10 [10^(-11)]` `=-[-11xxlog_10 10]` =-(-11)=11 pH+pOH =14 pH=14-pOH pH=14-11=3 |
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| 7074. |
A convex lens of power +4 D is brought in contact with a concave lens of power -2 D. The power of the lens combination is |
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Answer» `+6` D |
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| 7075. |
What do you mean by principal focus of a concave mirror ? |
| Answer» Solution :PRINCIPAL FOCUS of a concave mirror is a point situated on its principal AXIS where light rays coming parallel to the principal axis of mirror converge after REFLECTION. | |
| 7076. |
An object of height 2.5 cm is placed at a distance of 15 cm from the optical centre 'O' of a convex lens of focal length 10 cm. Draw a ray diagram to find the position and size of the image formed. Mark optical centre 'O', principal focus F and height of the image on the diagram. |
Answer» SOLUTION :
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| 7077. |
How much current will an electric heater coil draw from a 220 V source, if the resistance of the heater coil is 100 Omega? |
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Answer» SOLUTION :We are given, source voltage V = 220V, : Resistance of heater coil `R = 100 Omega`. Now, `V =IR` `:. I =V/R = 22 V//100 Omega = 2.2A` Important note: When different ELECTRICAL devices having different resistances areconnectedseparately to the same source, current drawn by them are different. |
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| 7078. |
Heat cannot flow itself from a body at lower temperature to a body athigher temperature is a statement or consequence of which law of thermo- dynamics ? |
| Answer» SOLUTION :SECOND LAW of THERMODYNAMICS. | |
| 7079. |
Prepare a list of five activities that you perform daily in which natural resource can be conserved or energy utilisation can be minimised. |
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Answer» Solution :Activities that we perform daily in which NATURAL resources cab be conserved or energy UTILISATION can be minimised are (i) Use fan the light only when required. Switch them off in unoccupied rooms. (ii) Use CFL in place of conventional bulbs/tubes. (iii) Avoid using a hose PIPE for watering plants as a lot of water is wasted through it. (iv) Use solar energy whenever possible. (v) Unused water in the water bottles may be used for watering plants. (vi) Close taps when not in use. (VII) Use public transport or car pools to save fuel. (viii) Use CNG as in alternative fuel. (ix) Pressure cookers should be used for cooking food to save fuels like LPG. (X) Use stairs to climb atleast upto three floors of building instead to taking lift. This will save electricity (any five). |
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| 7080. |
Human beings have important place in environment. |
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Answer» SOLUTION :(1) Man came last on the earth during evolution of animals. But due to his intelligence, imagination, critical thinking and memory, he made progress in all fields. (2) By virtue of these QUALITIES he became supreme and does not OBEY the rules of nature. (3) All the natural resources on the earth were very rapidly EXPLOITED by man.Under the pretext of technology and development he made degradation of almost all natural ecosystems. (4) Phenomena like pollution, urbanization,industrialization anddeforestation areexclusivelyhis CREATIONS. Hunting andpoaching other animals were his contribution to the extinctionof many other animals. (5) Except man no other organism on the earth can change the ecosystems in such a drastic way. Therefore, it is rightly said that human beings have important place in environment. |
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| 7081. |
The speed's hand of a which is 2cm long. Thespeed of the tip of this hand is |
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Answer» 0.21cm/s |
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| 7082. |
What can you say about the resistance of a voltmeter? |
| Answer» SOLUTION :The resistance of a voltmeter should be very high, IDEALLY INFINITE. | |
| 7083. |
{:(,"Column-I",,," Column-II"),(1,"Linearexpansion",-,(a),"change in volumne"),(2,"Superficial expanison",-,(b), "hot body to cold body"),(3,"Cubical expansion",-,(c),1.381xx10^(23)JK^(-1)),(4,"Heat transformation",-,(d),"change in length"),(5,"Boltzmann constant",-,(e), "change in area"):} |
| Answer» SOLUTION :1 (d) change in length 2(e) change in area (3) (a) change in VOLUME 4 (b) hot body to cold body 5 (C) `1.381xx10^(-23)JK^(-1)` | |
| 7084. |
A house has 3 tube lights of 20 watts each, On the average, all the tube lights are kept on for five hours. Find the energy consumed in 130 days. |
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Answer» Solution :NUMBER of TUBE lights =3 Wattge = 20 watts each CONSUMED hours = 5 hrs Energy `= (3 XX 20 xx5)/(1000)` `= (300)/(1000)` KWH = 0.3 KWH Consumed energy for 30 days `= 0.3 xx 30 = 9` KWH (or) 9 units. |
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| 7085. |
The unwanted earthly impurities like sand, limestone, rocky materials present in an ore are called : |
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Answer» Metallurgy |
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| 7086. |
Draw a simple diagram ofafire tongs and mark on it the fulcrum F and the points of application of load L and effort E. (a) Name the class of lever. (b) if load arm is 15 cm and effort arm is 5 cm. what is its mechanical adavantage? |
Answer» Solution :(a) FIGURE shows a fire tongs in which the effort E is in between the load L and fulcrum F. this belongs to class III levers.  (b) Given: load arm=15 CM, effort arm=5cm Mechanical advantage=`("effort arm")/("load arm")=(5)/(15)=(1)/(3)`. |
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| 7087. |
Draw a neat and well labelled ray diagram for image formation by a convex lens when an object is palced in front of the lence , betweenF_1 and 2F_1 |
Answer» SOLUTION :
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| 7088. |
Identify the following reactions the reactants that undergo oxidation and reduction.Fe + S to FeS |
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Answer» Solution :`Fe + S to FES` In this reaction, OXIDATION of Fe TAKES place and reduction of SULPHUR takes place. |
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| 7089. |
When white light passes through a glass prism |
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Answer» RED COLOURED RAY undergoes maximum deviation. |
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| 7090. |
What are the causes of Myopia? |
| Answer» SOLUTION :Myopia , also known as short SIGHTEDNESS , occurs due to the lengthening of EYE ball . With this defect , nearby objects can be SEEN clearly but DISTANCE objects cannot be seen clearly. | |
| 7091. |
Assertion : Bending of light rays from its original path at the interface of the two media is called 'Refraction'. Reason : Whenever the light travels from denser medium to rarer medium, it bends away from the normal. |
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Answer» Both ASSERTION and REASON are TRUE and reason is CORRECT EXPLANATION of assertion. |
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| 7092. |
What is the relation between the deviation of componenł colours of white light through a prism ańd their wavelength? |
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| 7093. |
State the reason for the following :Aluminium oxide is called an amphoteric oxide.(ii) An iron strip dipped in a blue copper sulphate solution turns the blue solution pale green.(iii) Hydrogen gas is not evolved when most metals react with nitric acid. (iv) Calcium does not occur in free state in nature.(v) Sodium or potassium metals are kept immersed under kerosene. |
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Answer» SOLUTION :(i) Aluminium oxide is amphoteric because it reacts with acids as well as bases. (ii) This is because iron is more reactive than copper in the reactivity SERIES. Zinc displace copper from copper sulphate solution and iron sulphate is formed. As there is no more copper sulphate in the solution, blue colour disapperars. As iron sulphate is formed, the solution BECOMES pale green. (iii) Nitric acid is a strong OXIDISING agent. Hydrogen gas formed is oxidised to water. (IV) Calcium is a reactive metal. It reacts with oxygen, water and other chemicals and occurs in combined state. (v) Sodium and potassium are very reactive metals. They react with oxygen forming oxides. They do not react with kerosene and remain protected from oxygen in the air. |
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| 7094. |
What is the range of wavelength of electromagnetic waves that constitute visible radiation ? |
| Answer» Solution :The range of electromagnetic WAVES is about `4000 Å " to " 7000 Å ` , which constitute VISIBLE radiation. | |
| 7095. |
What are the two factors on which the lateral displacement of an emergent ray from a glass slab depends? |
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Answer» SOLUTION :(i) ANGLE ofincidence (ii) Thickness of GLASS SLAB |
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| 7097. |
To doublethe voltage generated in a generator…… |
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Answer» the rotational speed of the coilshould behalvened . |
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| 7098. |
Heat energy is being produced in a resistance in a circuit at the rate of 99 W. The current of 3 A is flowing in the circuit. What must be the value of the resistance? |
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| 7099. |
Namethe instrumentused to determinethe directionof magnetic field . |
| Answer» SOLUTION :MAGNETICNEEDLE | |
| 7100. |
Assertion (A) : At high temperatures, metal wires have a greater chance of short circuiting. Reason (R) : Both resistance and resistivity of a material vary with temperature. |
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Answer» Both (A) and (R) are TRUE and (R) is correct explanation of the ASSERTION |
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