Practice Test


1) A constant volume gas thermometer works on


2) The wire used in resistance thermometer is platinum wire because


3) What is 273.00 K on the Celsius scale of temperature?


4) Expansion during heating


5) Which of the following temperatures is the highest?


6) By what factor, the volume of the metal submerged in mercury changes.


7) Mercury thermometer can be used to measure temperature up to


8) One fixed point of temperature used in the absolute scale is


9) Two spheres of same size are made of the same metal but one is hollow and the other is solid. They are heated to same temperature. Then


10) The ratio of the densities of the two bodies is 3 : 4 the ratio of specific heats is 4 : 3. The ratio of their thermal capacities for unit volume is


11) Recently, the phenomenon of super conductivity has been observed at 95 K. This temperature is nearly equal to


12) Statement 1: The ratio of specific heat capacity to molar heat capacity of a gas depends on the molecular mass of the gas.
Statement 2: One mole of the gas contains its molecular mass in grams.


13) The ratio of melting points of P to Q is :


14) The ratio of latent heats of fusion of P to Q is :


15) The ratio of specific heat of P to Q in solid state is :


16) On the Celsius scale the absolute zero of temperature is at


17) No other thermometer is as suitable as a platinum resistance thermometer to measure temperature in the entire range of


18) Absolute temperature can be calculated by


19) Thermoelectric thermometer is based on


20) The study of physical phenomenon at low temperatures (below liquid nitrogen temperature) is called


21) ‘Stem Correction’ in platinum resistance thermometers are eliminated by the use of


22) The absolute zero is the temperature at which


23) Absolute scale of temperature is reproduced in the laboratory by making use of a


24) Absolute zero (0 K) is that temperature at which


25) On which of the following scales of temperature, the temperature is never negative


26) One quality of a thermometer is that its heat capacity should be small. If P is a mercury thermometer, Q is a resistance thermometer and R thermocouple type then


27) Two thermometers are used to record the temperature of a room. If the bulb of one is wrapped in wet hanky


28) At what temperature the centigrade (Celsius) and Fahrenheit, readings are the same


29) Standardisation of thermometers is obtained with


30) The gas thermometers are more sensitive than liquid thermometers because


31) Mercury thermometers can be used to measure temperatures upto


32) A device used to measure very high temperature is


33) The absolute zero temperature in Fahrenheit scale is


34) A constant pressure air thermometer gave a reading of 47.5 units of volume when immersed in ice cold water, and 67 units in a boiling liquids. The boiling point of the liquid will be


35) Of the following thermometers, the one which can be used for measuring a rapidly changing temperature is a


36) On centigrade scale the temperature of a body increases by 30 degrees. The increase in temperature on Fahrenheit scale is


37) When a copper ball is heated, the largest percentage increase will occur in its


38) The apparent coefficient of expansion of a liquid when heated in a copper vessel is C and when heated in a silver vessel is S. If A is the linear coefficient of expansion of copper, then the linear coefficient of expansion of silver is


39) When a rod is heated but prevented from expanding, the stress developed is independent of


40) Expansion during heating


41) When a bimetallic strip is heated, it


42) A solid ball of metal has a concentric spherical cavity within it. If the ball is heated, the volume of the cavity will


43) A litre of alcohol weighs


44) 5 litre of benzene weighs


45) Water has maximum density at


46) At some temperature T, a bronze pin is a little large to fit into a hole drilled in a steel block. The change in temperature required for an exact fit is minimum when


47) If the length of a cylinder on heating increases by 2%, the area of its base will increase by


48) In cold countries, water pipes sometimes burst, because


49) A brass disc fits simply in a hole of a steel plate. The disc from the hole can be loosened if the system


50) When vapour condenses into liquid


51) If specific heat of a substance is infinite, it means


52) A quantity of heat required to change the unit mass of a solid substance, from solid state to liquid state, while the temperature remains constant, is known as


53) The latent heat of vaporization of a substance is always


54) The factor not needed to calculate heat lost or gained when there is no change of state is


55) Water is used to cool radiators of engines, because


56) Melting point of ice


57) Two spheres made of same substance have diameters in the ratio 1 : 2. Their thermal capacities are in the ratio of


58) If mass energy equivalence is taken into account, when water is cooled to form ice, the mass of water should


59) Amount of heat required to raise the temperature of a body through 1K is called its


60) A liquid of mass m and specific heat c is heated to a temperature 2T. Another liquid of mass m/2 and specific heat 2c is heated to a temperature T. If these two liquids are mixed, the resulting temperature of the mixture is


61) By exerting a certain amount of pressure on an ice block, you


62) A water fall is 84 metres high. If half of the potential energy of the falling water gets converted to heat, the rise in temperature of water will be


63) A body of mass 5 kg falls from a height of 30 metre. If its all mechanical energy is changed into heat, then heat produced will be


64) In supplying 400 calories of heat to a system, the work done will be


65) 0.93 watt-hour of energy is supplied to a block of ice weighing 10 gm. It is found that


66) The temperature of Bhakhra dam water at the ground level with respect to the temperature at high level should be


67) The SI unit of mechanical equivalent of heat is


68) Of two masses of 5 kg each falling from height of 10 m, by which 2kg water is stirred. The rise in temperature of water will be


69) A lead ball moving with a velocity V strikes a wall and stops. If 50% of its energy is converted into heat, then what will be the increase in temperature (Specific heat of lead is S)


70) The mechanical equivalent of heat J is


71) Water falls from a height of 210m. Assuming whole of energy due to fall is converted into heat the rise in temperature of water would be (J = 4.3 Joule/cal)


72) A block of mass 100 gm slides on a rough horizontal surface. If the speed of the block decreases from 10 m/s to 5 m/s, the thermal energy developed in the process is


73) 4200 J of work is required for


74) In a water-fall the water falls from a height of 100 m. If the entire K.E. of water is converted into heat, the rise in temperature of water will be


75) A lead bullet of 10 g travelling at 300 m/s strikes against a block of wood and comes to rest. Assuming 50% of heat is absorbed by the bullet, the increase in its temperature is
(Specific heat of lead = 150J/kg, K)


76) The temperature at which the vapour pressure of a liquid becomes equals to the external (atmospheric) pressure is its


77) Calorimeters are made of which of the following


78) A liquid boils when its vapour pressure equals


79) The amount of work, which can be obtained by supplying 200 cal of heat, is


80) During constant temperature, we feel colder on a day when the relative humidity will be


81) Which of the following is the unit of specific heat


82) The freezing point of the liquid decreases when pressure is increased, if the liquid


83) Latent heat of 1gm of steam is 536 cal/gm, then its value in joule/kg is


84) Which of the following has maximum specific heat


85) The point on the pressure temperature phase diagram where all the phases co-exist is called


86) Boiling water is changing into steam. At this stage the specific heat of water is


87) The thermal capacity of a body is 80 cal, then its water equivalent is


88) A liquid of mass M and specific heat S is at a temperature 2t. If another liquid of thermal capacity 1.5 times, at a temperature of t/3 is added to it, the resultant temperature will be


89) Dry ice is


90) Solids expand on heating because


91) Two metal strips that constitute a thermostat must necessarily differ in their


92) If a liquid is heated in weightlessness, the heat is transmitted through


93) If black wire of platinum is heated, then its colour first appear red, then yellow and finally white. It can be understood on the basis of


94) The freezing point of the liquid decreases when pressure is increased, if the liquid


95) Let there be four articles having colours blue, red, black and white. When they are heated together and allowed to cool, which article cool at the earliest


96) Woolen clothes are used in winter season because woolen clothes


97) Which of the following statements is true/correct


98) For a perfectly black body, its absorptive power is


99) Which of the following is the unit of specific heat


100) The cause of Fraunhoffer lines is


101) The quantity of heat which crosses per unit area of a metal plate during conduction depends upon


102) The luminosity of the Rigel star is 17000 times that of the sun. Assume both to be perfectly black bodies. If the surface temperature of the sun is 6000 K, then the temperature of the star is


103) Of the following thermometers, the one which can be used for measuring a rapidly changing temperature is a


104) A metal sphere of radius r and specific heat c is rotated about an axis passing through its centre at a speed of n rotations per second. It is suddenly stopped and 50% of its energy is used in increasing its temperature. Then the rise in temperature of the sphere is


105) The spectrum from a black body radiation is a


106) The amount of radiation emitted by a perfectly black body is proportional to


107) One gram of ice is mixed with one gram of steam. At thermal equilibrium the temperature of mixture is


108) Which one of the following processes depends on gravity?


109) Four pieces of iron heated in a furnace to different temperatures show different colours listed below. Which one has the highest temperature


110) Boiling water is changing into steam. At this stage then specific heat of water is


111) Two metal strips that constitute a thermostat must necessarily differ in their


112) An ideal black body at room temperature is thrown into a furnance. It is observed that


113) Two beakers A and B are filled to the brim with water at 4℃. When A is heated and B is cooled, the water


114) The sprinkling of water reduces slightly the temperature of a closed room because


115) In MKS system, Stefan’s constant is denoted by σ. In CGS system multiplying factor of σ will be


116) A gas in an airtight container is heated from 25℃ to 90℃. The density of the gas will


117) Work done in converting one gram of ice at -10℃ into steam at 100℃ is


118) A sphere, a cube and a thin circular plate, all made of the same material and having the same mass are initially heated to a temperature of 1000℃. Which one of these will cool first


119) If the temperature of a hot body is increased by 50% then the increase in the quantity of emitted heat radiation will be


120) Heat capacity of a substance is infinite. It means


121) It is known that wax contracts on solidification. If molten wax is taken in a large vessel and it is allowed to cool slowly, then


122) At a common temperature, a block of wood and a block of metal feel equally cold or hot. The temperature of block of wood and block of metal are


123) A faulty thermometer has its fixed points marked 5 and 95. When this thermometer reads 68, the correct temperature in Celsius is


124) Newton’s law of cooling is used in laboratory for the determination of the


125) No other thermometer is as suitable as a platinum resistance thermometer to measure temperature in the entire range of


126) A hollow copper sphere S and a hollow copper cube C, both of negligible thin walls of same area, are filled with water at 90℃ and allowed to cool in the same environment. The graph that correctly represents their cooling is


127) Three identical rods A,B and C are placed end to end. A temperature difference is maintained between the free ends of A and C. The thermal productivity of B is thrice that if C and half of that of A. the effective thermal conductivity of the system will be (KA is the thermal conductivity of rod A)


128) In a pressure cooker, cooking is faster because the increase of vapour pressure


129) A gas undergoes an adiabatic change. Its specific heat in the process is


130) 1 g of a steam at 100℃ melts how much ice at 0℃? (Latent heat of ice =80 cal/gm and latent heat of steam =540 cal/gm )


131) The temperature, at which Centigrade and Fahrenheit scales give the same reading is


132) There are two spherical balls A and B of the same material with same surface, but the diameter of A is half that of B. If A and B are heated to the same temperature and then allowed to cool, then


133) The maximum energy in thermal radiation from a source occurs at the wavelength 4000Å. The effective temperature of the source is


134) The temperature at which a black body of unit area loses its energy at the rate of 1 joule/second is


135) An experiment takes 10 min to raise temperature of water from 0℃ and 100℃ and another 55 min to convert it totally into steam by a stabilized heater. The latent heat of vaporization comes out to be


136) A calorimeter of mass 0.2 kg and specific heat 900 J/kg-K. Containing 0.5 kg of a liquid of specific heat 2400 J/kg-K. Its temperature falls from 60℃ to 55℃ in one minute. The rate of cooling is


137) A partition wall has two layers A and B in contanct, each made of a different material. They have the same thickness but the thermal conductivity of layer A is twice that of layer B. If the steady state temperature difference across the wall is 60K, then the corresponding difference across the layer A is


138) In supplying 400 calories of heat to a system, the work done will be


139) A block of mass 100 gm slides on a rough horizontal surface. If the speed of the block decreases from 10 m/s to 5 m/s, the thermal energy developed in the process is


140) Three very large plates of same area are kept parallel and close to each other. They are considered as ideal black surfaces and have very high thermal conductivity. The first and third plates are maintained at temperatures 2T and 3T respectively. The temperature of the middle (i.e. second) plate under steady state condition is


141) Water falls from a height of 500 m. What is the rise in temperature of water at the bottom if whole energy is used up in heating water?


142) Standardisation of thermometers is obtained with


143) If a black body is heated at a high temperature, it seems to be


144) The absolute zero temperature in Fahrenheit scale is


145) The lengths and radii of two rods made of same material are in the ratios 1:2 and 2:3 respectively. If the temperature difference between the ends for the two rods be the same, then in the steady state, the amount of heat flowing per second through them will be in the ratio


146) Triple point of water is


147) When vapour condenses into liquid


148) Which of the following statements is wrong


149) If l is length A is the area of cross section and K is thermal conductivity, then the thermal resistance of the block is given by


150) Which of the following is the example of ideal black body


151) A block of metal is heated to a temperature much higher than the room temperature and allowed to cool in a room free from air currents. Which of the following curves correctly represents the rate of cooling


152) The heat is flowing through two cylindrical rods of same material. The diameters of the rods are in the ratio 1:2 and their lengths are in the ratio 2:1. If the temperature difference between their ends is the same, the ratio of rate of flow of heat through them will be


153) A metallic ball and highly stretched spring are made of the same material and have the same mass. They are heated so that they melt, the latent heat required


154) The temperature of equal masses of three different liquids A, B and C are 12℃, 19℃ and 28℃ respectively. The temperature when A and B are mixed is 16℃ and when B and C are mixed is 23℃. The temperature when A and C are mixed is


155) Two spheres made of same material have radii in the ratio 2:1. If both the spheres are at same temperature, then what is the ration of heat radiation energy emitted per second by them?


156) The original temperature of a black body is 727℃. The temperature at which this black body must be raised so as to double the total radiant energy, is


157) Latent heat of 1gm of steam is 536 cal/gm, then its value in joule/kg is


158) On a hilly region, water boils at 95°C.The temperature expressed in Fahrenheit is


159) The gas thermometers are more sensitive than liquid thermometers because


160) Two rectangular blocks A and B of different metals have same length and same area of cross-section. They are kept in such a way that their cross-sectional area touch each other. The temperature at one end of A is 100℃ and that of B at the other end is 0℃. If the ratio of their thermal conductivity is 1 : 3, then under steady state, the temperature of the junction in contact will be


161) The volume of a metal sphere increases by 0.24% when its temperature is raised by 40℃ . The coefficient of linear expansion of the metal is …/℃.


162) Flash light equipped with a new set of batteries, produces bright white light. As the batteries were out


163) For proper ventilation of building, windows must be open near the bottom and top of the walls so as to let pass


164) Two thermometers A and B are exposed in sun light. The valve of A is painted black, but that of B is not painted. The correct statement regarding this case is


165) A piece of glass is heated to a high temperature and then allowed to cool. If it cracks, a probable reason for this is the following property of glass


166) When two ends of a rod wrapped with cotton are maintained at different temperatures and after same time every point of the rod attains a constant temperature, then


167) A body radiates energy 5W at a temperature of 127℃. If the temperature is increased to 927℃, then it radiates energy at the rate of


168) In a radiation spectrum obtained from a furnace of 2600 K has maximum intensity at 12000 Å wavelength. If the maximum intensity in spectrum of a star is at 5000 A. the temperature of the outer surface of star is


169) The point on the pressure-temperature phase diagram where all the three phases co-exist is called


170) Distribution of energy in the spectrum of a black body can be correctly represented by


171) A solid cube and a solid sphere of the same material have equal surface area. Both are at the same temperature 120℃, then


172) If the initial temperatures of metallic sphere and disc, of the same mass, radius and nature are equal, then the ratio of their rate of cooling in same environment will be


173) Colour of shinning bright star is an indication of its


174) Water is used to cool the radiators of engines in cars because


175) A closed bottle containing water at 30℃ is carried to the moon in a space-ship. If it is placed on the surface of the moon, what will happen to the water as soon as the lid is opened


176) The factor not needed to calculate heat lost or gained when there is no change of state is


177) A black metal foil is warmed by radiation from a small sphere at temperature and at a distance . It is found that the power received by the foil is . If both the temperature and the distance are doubled, the power received by the foil will be


178) 16:1 The ratio of radiant energies radiated per unit surface area by two bodies is 16:1, the temperature of hotter body is 1000K, then the temperature of colder body will be


179) It is difficult to cook rice in an open vessel by boiling it a high altitudes because of


180) A solid ball of metal has a concentric spherical cavity within it. If the ball is heated, the volume of the cavity will


181) The variation of density of water with temperature is represented by the


182) During constant temperature, we feel colder on a day when the relative humidity will be


183) “Good emitters are good absorbers” is a statement concluded from


184) Water has maximum density at


185) Amount of heat required to raise the temperature of a body through 1K is called its


186) Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 minutes and 30 minutes. The ratio of their thermal conductivities will be


187) A brass disc fits simply in a hole of a steel plate. The disc from the hole can be loosened if the system


188) Which of the following has maximum specific heat


189) When the room temperature becomes equal to the dew point, the relative humidity of the room is


190) The temperature of a piece of iron is 27℃ and it is radiating energy at the rate of Q kWm^(-2). If its temperature is raised to 151℃, the rate of radiation of energy will become approximately


191) Two rods of same length and material transfer a given amount of heat in 12 s, when they are joined end to end (i.e, in series). But when they are joined in parallel, they will transfer same heat under same conditions in


192) Heat is flowing through a conductor of length l from x=0 to x=l. If its thermal resistance per unit length is uniform, which of the following graphs is correct


193) The wavelength of radiation emitted by a body depends upon


194) The temperature of the sun is measured with


195) By increasing the temperature of a liquid its


196) Dry ice is


197) The latent heat of vaporization of a substance is always


198) If the temperature of the sun becomes twice its present temperature, then


199) The temperature gradient in a rod of 0.5 m long is 80℃/m. If the temperature of hotter end of the rod is 30℃, then the temperature of the cooler end is


200) For cooking the food, which of the following type of utensil is most suitable


201) Good absorbers of heat are


202) In heat transfer, which method is based on gravitation


203) At some temperature T, a bronze pin is a little large to fit into a hole drilled in a steel block. The change in temperature required for an exact fit is minimum when


204) Which of the prism is used to see infra-red spectrum of light


205) There is a rough black spot on a polished metallic plate. It is heated upto 1400 K approximately and then at once taken in a dark room. Which of the following statements is true


206) Suppose the sun expands so that its radius becomes 100 times its present radius and its surface temperature becomes half of its present value. The total energy emitted by it then will increase by a factor of


207) Two identical plates of different metals are joined to form a single plate whose thickness is double the thickness of each plate. If the coefficients of conductivity of each plate are 2 and 3 respectively, then the conductivity of composite plate will be


208) When red glass is heated in dark room it will seen


209) Two thermometers are used to record the temperature of a room. If the bulb of one is wrapped in wet hanky


210) Wien’s displacement law for emission of radiation can be written as


211) Amount of heat required to convert 10 g of ice to water at 20℃ is


212) On investigation of light from three different stars A,B and C, it was found that in the spectrum of A the intensity of red colour is maximum, in B the intensity of blue colour is maximum and in C the intensity of yellow colour is maximum. From these observations it can be concluded that


213) A body has same temperature as that of the surrounding. Then


214) A substance of mass m kg requires a power input of P watts to remain in the molten state at its melting point. When the power is turned off, the sample completely solidifies in time t sec. What is the latent heat of fusion of the substance


215) If the temperature of the sun were to increase from T to 2T and its radius from R to 2R, when the ratio of radiant energy received on earth to what it was previously, will be


216) If the radius of a star is R and it acts as a black body, what would be the temperature of the star, in which the rate of energy production is Q


217) Newton’s law of cooling holds good only, if the temperature difference between the body and the surroundings is


218) A hot body will radiate heat most rapidly if its surface is


219) It is hotter for the same distance over the top of a fire than it is in the side of it, mainly because


220) When a copper ball is heated, the largest percentage increase will occur in its


221) Two spheres of radii in the ratio 1:2 and densities in the ratio 2:1 and of same specific heat, are heated to same temperature and left in the same surrounding. Their rate of cooling will be in the ratio


222) If a black body emits 0.5 J of energy per second when it is at 27℃, then the amount of energy emitted by it when it is at 627℃ will be


223) If a graph is plotted taking the temperature in Fahrenheit along Y-axis and the corresponding temperature in Celsius along the X-axis, it will be a straight line


224) The absolute temperatures of two black bodies are 2000 K and 3000 K respectively. The ratio of wavelengths corresponding to maximum emission of radiation by them will be


225) A constant volume gas thermometer shows pressure reading of 50 cm and 90 cm of mercury at 0℃ and 100℃ respectively. When the pressure reading is 60 cm of mercury, the temperature is


226) A hot and a cold body are kept in vacuum separated from each other. Which of the following cause decrease in temperature of the hot body


227) An object is at a temperature of 400℃. At what temperature would it radiate energy twice as fast? The temperature of the surroundings may be assumed to be negligible


228) Four rods of different radii r and length l are used to connect two reservoirs of heat at different temperatures. Which one will conduct heat fastest?


229) A body initially at 80℃ cools to 64℃ in 5 min and to 52℃ in 10 min. the temperature of the surrounding is


230) When a rod is heated but prevented from expanding, the stress developed is independent of


231) Which of the following cylindrical rods will conduct most heat, when their ends are maintained at the same steady temperature


232) If the temperature of a hot body is increased by 50% then the increase in the quantity of emitted heat radiation will be


233) The thermal conductivity of a rod is 2. What is its thermal resistivity?


234) Newton’s law of cooling is a special case of


235) The spectral energy distribution of a star is maximum at twice temperature as that of sun. the total energy radiated by star is


236) On a cold morning, a metal surface will feel colder to touch than a wooden surface because


237) In which process, the rate of transfer of heat is maximum


238) The temperature at which the vapour pressure of a liquid becomes equals to the external (atmospheric) pressure is its


239) The thermal radiation from a hot body travels with a velocity of


240) A vessel contains 110 g of water. The heat capacity of the vessel is equal to 10 g of water. The initial temperature of water in vessel in 10℃. If 220 g of hot water at 70C is poured in the vessel, the final temperature neglecting radiation loss will be


241) A brass disc fits simply in a hole of a steel plate. The disc from the hole can be loosened if the system


242) The study of physical phenomenon at low temperatures (below liquid nitrogen temperature) is called


243) Solids expand on heating because


244) Melting point of ice


245) When a bimetallic strip is heated, it


246) The temperature at which a black body ceases to radiate energy, is


247) For an opeque body coefficient of transmission is


248) If temperature of an object is 140⁰ F, then its temperature in centigrade is


249) An amount of water of mass 20 g at 0℃ is mixed with 40 g of water 10℃, final temperature of the mixture is


250) On the Celsius scale the absolute zero of temperature is at


251) Mud houses are cooler in summer and warmer in winter because


252) Mode of transmission of heat, in which heat is carried by the moving particles, is


253) A constant pressure air thermometer gave a reading of 47.5 units of volume when immersed in ice cold water, and 67 units in a boiling liquids. The boiling point of the liquid will be


254) In the Ingen Hauz’s experiment the wax melts up to lengths 10 and 25cm on two identical rods of different materials. The ratio of thermal conductivities of the two material is


255) The amount of heat conducted out per second through a window, when inside temperature is 10℃ and outside temperature is -10℃, is 1000 J. Same heat will be conducted in through the window, when outside temperature -23℃ and inside temperature is


256) The rate of radiation of a black body at 0℃ is EJ/s. The rate of radiation of this black body at 273℃ will be


257) Calculate the amount of heat (in calories) required to convert 5 g of ice at 0℃ to steam at 100℃


258) There are two identical vessels filled with equal amounts of ice. The vessels are of different metals., If the ice melts in the two vessels in 20 and 35 minutes respectively, the ratio of the coefficients of thermal conductivity of the two metals is


259) On heating, the temperature at which water has minimum volume is


260) In a water-fall the water falls from a height of 100m. If the entire K.E. of water is converted into heat, the rise in temperature of water will be


261) The dimensions of thermal resistance are


262) A black body is at a temperature 300 K. It emits energy at a rate, which is proportional to


263) The saturation vapour pressure of water at 100℃ is


264) Hot water cools from 60℃ to 50℃ in the first 10 min and to 42℃ in the first 10 min and to 42℃ in the next 10 min. Then the temperature of the surroundings is


265) A black body radiates 20 Wat temperature 227℃. If temperature of the black body is changed to 727℃ then its radiating power will be


266) The absolute zero is the temperature at which


267) Mercury boils at 367°C.However,mercury thermometers are made such that they can measure temperature are made such that they can measure temperature upto 500°C.This is done by


268) No other thermometer is as suitable as a platinum resistance thermometer to measure temperature in the entire range of


269) Three identical rods A,B and C are placed end to end. A temperature difference is maintained between the free ends of A and C. The thermal productivity of B is thrice that if C and half of that of A. the effective thermal conductivity of the system will be (KA is the thermal conductivity of rod A)


270) A gas undergoes an adiabatic change. Its specific heat in the process is


271) On Centigrade scale the temperature of a body increases by 30°.The increase in temperature on Fahrenheit scale is


272) The Fahrenheit and Kelvin scales of temperature will give the same reading at


273) Four rods of silver, copper, brass and wood are of same shape. They are heated together after wrapping a paper on it, the paper will burn first on


274) In which mode of transmission, the heat waves travel along straight line with the speed of light?


275) One quality of a thermometer is that its heat capacity should be small. If P is a mercury thermometer, Q is a resistance thermometer and R thermocouple type then


276) We consider the radiation emitted by the human body. Which of the following statements is true?


277) Equal masses of two liquids are filled in two similar calorimeters. The rate of cooling will


278) The wavelength of the radiation emitted by a body depends upon


279) Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in 20 minutes and 40 minutes respectively. The ratio of thermal conductivities of the materials is


280) The intensity of radiation emitted by the sun has its maximum value at a wavelength of 510 nm and that emitted by the north star has the maximum value at wavelength of 350 nm. If these stars behave like black bodies, then the ratio of surface temperatures of the sun and north star is


281) Thermoelectric thermometer is based on


282) At NTP water boils at 100℃. Deep down the mine, water will boil at a temperature


283) Two spheres of radii 8 cm and 2 cm are cooling. Their temperatures are 127℃ and 527℃ respectively. Find the ratio of energy radiated by them in the same time


284) Expansion during heating


285) The velocity of heat radiation in vacuum is


286) The amount of work, which can be obtained by supplying 200 cal of heat, is


287) The surface temperature of the stars is determined using


288) The luminosity of the Rigel star is 17000 times that of the sun. Assume both to be perfectly black bodies. If the surface temperature of the sun is 6000 K, then the temperature of the star is


289) The initial temperature of a body is 80℃. If its temperature falls to 64℃ in 5 minutes and in 10 minutes to 52℃ then the temperature of surrounding will be


290) 80 gm of water at 30℃ are poured on a large block of ice at 0℃. The mass of ice that melts is


291) Latent heat of 1gm of steam is 536 cal/gm, then its value in joule/kg is


292) On a hilly region, water boils at 95°C.The temperature expressed in Fahrenheit is


293) The gas thermometers are more sensitive than liquid thermometers because


294) For proper ventilation of building, windows must be open near the bottom and top of the walls so as to let pass


295) Two thermometers A and B are exposed in sun light. The valve of A is pointed black, but that of B is not pointed. The correct statement regarding this case is


296) A piece of glass is heated to a high temperature and then allowed to cool. If it cracks, a probable reason for this is the following property of glass


297) When two ends of a rod wrapped with cotton are maintained at different temperatures and after same time every point of the rod attains a constant temperature, then


298) In a radiation spectrum obtained from a furnace of 2600 K has maximum intensity at 12000 Å wavelength. If the maximum intensity in spectrum of a star is at 5000 A. the temperature of the outer surface of star is


299) Distribution of energy in the spectrum of a black body can be correctly represented by


300) Which of the following circular rods. (given radius r and length l) each made of the same material as whose ends are maintained at the same temperature will conduct most heat?


301) 2 g of water condenses when passed through 40 g of water initially at 25℃. The condensation of steam raises the temperature of water to 54.3℃. What is the latent heat of steam?


302) A block of ice at -10° c slowly heated and converted to steam at 100℃. Which of the following curves represents this phenomenon qualitatively?


303) A thermos flask is polished well


304) As compared to the person with white skin, the person with black skin will experience


305) When the pressure on water is increased the boiling temperature of water as compared to 100℃ will be


306) Which one of the figure gives the temperature dependence of density water correctly?


307) In order that the heat flows from one part of a solid to another part, what is required


308) The SI unit of mechanical equivalent of heat is


309) The mechanical equivalent of heat J is


310) A piece of blue glass heated to a high temperature and a piece of red glass at room temperature, are taken inside a dimly lit room then


311) In determining the temperature of a distant star, one makes use of


312) The energy supply being cut-off, an electric heater element cools down to the temperature of its
surroundings, but it will not cool further because


313) Two spheres of radii 8 cm and 2 cm are cooling. Their temperatures are 127℃ and 527℃ respectively. Find the ratio of energy radiated by them in the same time.


314) There is a black spot on a body. If the body is heated and carried in dark room then it glows more. This can be explained on the basis of


315) An iron bar of length l and having a cross-section A is heated from 0 to 100℃. If this bar is so held that it is not permitted to expand or bend, the force that is developed, is


316) A black body is heated from 27℃ to 127℃. The ratio of their energies of radiations emitted will be


317) Which of the following is the correct device for the detection of thermal radiation


318) Two bodies A and B having temperatures 327℃ and 427℃ are radiating heat to the surrounding. The surrounding temperature is 27℃ . The ration of rate of heat radiation of A to that of B is


319) In a steady state of thermal conduction, temperature of the ends A and B of a 20 cm long rod are 100℃ and 0℃ respectively. What will be the temperature of the rod at a point at a distance of 6 cm from the end A of the rod


320) A vertical column 50 cm long at 50℃ balances another column of same liquid 60 cm long at 100℃. The coefficient of absolute expansion of the liquid is


321) Absolute zero (0 K) is that temperature at which


322) Absorption co-efficient of an open window is


323) A perfect black body is one whose emissive power is


324) Which one of the following would raise the temperature of 20 g of water at 30℃ most when mixed with it?


325) A rectangular block is heated from 0℃ to 100℃. The percentage increase in its length is 0.2%. What is the percentage increase in its volume?


326) Absolute temperature can be calculated by


327) If temperature of a black body increases from 7℃ to 287℃, then the rate of energy radiation increases by


328) If earth suddenly stops rotating about its own axis, the increase in it’s temperature will be


329) The radiation emitted by star A is 10,000 times that of the sun. If the surface temperature of the sun and the star A are 6000k and 2000k respectively, the ratio of the radii of the star A and the sun is


330) The temperature of a liquid drops from 365k to 361K in 2 minutes. Find the time during which temperature of the liquid drops from 344k to 342K. Temperature of room is 293K.


331) Which of the following statements is correct


332) Can we boil water inside the earth satellite by convection


333) There is a black spot on a body. If the body is heated and carried in dark room then it glows more. This can be explained on the basis of