One kilogram of ice at C is mixed with one kilogram of water at 80. The final temperature of the mixture is (Take: Specific heat of water = 4200 J , Latent heat of ice = 336 kJ )
(1) C (2)
(3) (4)
1. 15 g
2. 30 g
3. 50 g
4 60 g
A black body at temperature 300K radiates heat at the rate E. If its temperature is increased by 600K, the rate of radiation will increase to -
1. 16E
2. 64E
3. 81E
4. 256E
Heat capacity is equal to the product of:
1. mass and gas constant
2. mass and specific heat
3. latent heat and volume of water
4. mass and Avogadro number
When a block of iron floats in Hg at , a fraction of its volumen= is submerged, while at temperature of a fraction is seen to be submersed. If the coefficient of volume expansion of iron is and that of mercury is , then the ratio can be expressed as:
1.
2.
3.
4.
1.
2.
3.
4.
A pendulum clock runs faster by 5 seconds per day at \(20^{\circ}\mathrm {C}\) and goes slow by 10 second per day at \(35^{\circ}\mathrm {C}\). It shows the correct time at a temperature of:
1. \(27.5^{\circ}\mathrm {C}\)
2. \(25^{\circ}\mathrm {C}\)
3. \(30^{\circ}\mathrm {C}\)
4. \(33^{\circ}\mathrm {C}\)
A constrained steel rod of length l, area of cross-section A, Young's modulus Y and coefficient of linear expansion is heated through \(t^{\circ}\mathrm{C}\). The work that can be performed by the rod when heated is:
1. (YAt)(lt)
2. (YAt)(lt)
3. (YAt)(lt)
4. 2(YAt)(lt)
Two identical bodies are made of a material for which the heat capacity increases with temperature. One of these is at C, while the other one is at C. If the two bodies are brought into contact, then assuming no heat loss, the final common temperature is -
(1)
(2) more than C
(3) less than C but greater than C
(4)
A piece of ice falls from a height \(h\) so that it melts completely. Only one-quarter of the heat produced is absorbed by the ice, and all energy of ice gets converted into heat during its fall. The value of \(h\) is: (Latent heat of ice is \(3.4\times10^5\) J/kg and \(g=10\) N/kg)
1. | \(544\) km | 2. | \(136\) km |
3. | \(68\) km | 4. | \(34\) km |
The value of coefficient of volume expansion of glycerin is 5x10-4 K-1. The fractional change in the density of glycerin for a rise of 40°C in its temperature is -
(1) 0.015
(2) 0.020
(3) 0.025
(4) 0.010
Steam at 100°C is passed into 20 g of water at 10°C. When water acquires a temperature of 80°C, the mass of water present will be (Take specific heat of water=1 cal g-1 °C-1 and latent heat of steam = 540 cal g-1)
(a) 24 g
(b) 31.5g
(c) 42.5 g
(d) 22.5 g
An ideal gas goes from state A to state B via three different processes, as indicated in the P-V diagram. If indicates the heat absorbed by the gas along the three processes and indicates the change in internal energy along the three processes respectively, then:
1. | \(\mathrm{Q}_1>\mathrm{Q}_2>\mathrm{Q}_3 \) and \(\Delta \mathrm{U}_1=\Delta \mathrm{U}_2=\Delta \mathrm{U}_3\) |
2. | \(\mathrm{Q}_3>\mathrm{Q}_2>\mathrm{Q}_1\) and \(\Delta \mathrm{U}_1=\Delta \mathrm{U}_2=\Delta \mathrm{U}_3\) |
3. | \(\mathrm{Q}_1=\mathrm{Q}_2=\mathrm{Q}_3\) and \(\Delta \mathrm{U}_1>\Delta \mathrm{U}_2>\Delta \mathrm{U}_3\) |
4. | \(\mathrm{Q}_3>\mathrm{Q}_2>\mathrm{Q}_1\) and \(\Delta \mathrm{U}_1>\Delta \mathrm{U}_2>\Delta \mathrm{U}_3\) |
A metal bar of length \(L\) and area of cross-section \(A\) is clamped between two rigid supports. For the material of the rod, its Young’s modulus is \(Y\) and the coefficient of linear expansion is \(\alpha\). If the temperature of the rod is increased by \(\Delta t^{\circ} \mathrm{C}\), the force exerted by the rod on the supports will be:
1. \(YAL\Delta t\)
2. \(YA\alpha\Delta t\)
3. \(\frac{YL\alpha\Delta t}{A}\)
4. \(Y\alpha AL\Delta t\)
The coefficient of linear expansion of brass and steel are and . If we take a brass rod of length and steel rod of length at 0°C, their difference in length will remain the same at a temperature if
(a) (b)
(c) (d)
Heat travels through vacuum by
(1) Conduction
(2) Convection
(3) Radiation
(4) Both (a) and (b)
Taking into account the radiation that a human body emits which of the following statements is true?
1. | The radiation is emitted only during the day. |
2. | The radiation is emitted during the summers and absorbed during the winters. |
3. | The radiation emitted lies in the ultraviolet region and hence is not visible. |
4. | The radiation emitted is in the infra-red region. |
Certain substance emits only the wavelengths and when it is at a high temperature. When this substance is at a colder temperature, it will absorb only the following wavelengths ?
(a) (b)
(c) and (d) and
As compared to the person with white skin, the person with black skin will experience
(1) Less heat and more cold
(2) More heat and more cold
(3) More heat and less cold
(4) Less heat and less cold
If between wavelength and , and be the emissive and absorptive powers of a body and be the emissive power of a perfectly black body, then according to Kirchoff's law, which is true ?
(1) = =
(2) =
(3) =
(4) = constant
When p calories of heat is given to a body, it absorbs q calories; then the absorbtion power of body will be ?
(1) p/q
(2) q/p
(3)
(4)
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 ?
(1) In comparison with the plate, the spot will shine more
(2) In camparison with the plate, the spot will appear more black
(3) The spot and the plate will be equally bright
(4) The plate and the black spot can not be seen in the dark room
A black body of surface area 10 is heated to 127°C and is suspended in a room at temperature 27°C. The initial rate of loss of heat from the body at the room temperature will be
(1) 2.99 W
(2) 1.89 W
(3) 1.18 W
(4) 0.99 W
Two identical objects A and B are at temperatures and respectively. Both objects are placed in a room with perfectly absorbing walls maintained at temperatures T(>T>). The objects A and B attain temperature T eventually. Which one of the following is the correct statement?
(1) ‘A’ only emits radiations while B only absorbs them until both attain temperature
(2) A loses more radiations than it absorbs while B absorbs more radiations than it emits until temperature T is attained
(3) Both A and B only absorb radiations until they attain temperature T
(4) Both A and B only emit radiations until they attain temperature T
When the body has the same temperature as that of surroundings
(1) It does not radiate heat
(2) It radiates the same quantity of heat as it absorbs
(3) It radiates less quantity of heat as it receives from surroundings
(4) It radiates more quantity of heat as it receives heat from surroundings
The temperature of a liquid drops from 365 K to 361 K in 2 minutes. Find the time during which temperature of the liquid drops from 344 K to 342 K . Temperature of room is 293 K
(a) 84 sec (b) 72 sec
(c) 66 sec (d) 60 sec
Newton’s law of cooling, holds good only if the temperature difference between the body and the surroundings is
(1) Less than 10
(2) More than 10
(3) Less than 100
(4) More than 100
The temperature of a body falls from 50 to 40 in 10 minutes. If the temperature of the surroundings is 20, then temperature of the body after another 10 minutes will be-
(1) 36.6
(2) 33.3
(3) 35
(4) 30
A body takes \(5\) minutes to cool from \(90^{\circ}\text{C}\) to \(60^{\circ}\text{C}\). If the temperature of the surroundings is \(20^{\circ}\text{C}\), the time taken by it to cool from \(60^{\circ}\text{C}\) to \(30^{\circ}\text{C}\) will be:
1. \(5~\text{min}\)
2. \(8~\text{min}\)
3. \(11~\text{min}\)
4. \(12~\text{min}\)
An object is cooled from 75°C to 65°C in 2 minutes in a room at 30°C. The time taken to cool another object from 55°C to 45°C in the same room in minutes is -
(1) 4
(2) 5
(3) 6
(4) 7
A cane is taken out from a refrigerator at 0°C. The atmospheric temperature is 25°C. If is the time taken to heat from 0°C to 5°C and is the time taken from 10°C to 15°C, then
(1)
(2)
(3)
(4) There is no relation
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°C. Which one of these will cool first ?
(1) Plate
(2) Sphere
(3) Cube
(4) None of these
A black metal foil is warmed by radiation from a small sphere at temperature T and at a distance d where surrounding temperature is . It is found that the power received by the foil is P. If both the temperature and the distance are doubled, the power received by the foil will be - [Assume ]
1. 16P
2. 4P
3. 2P
4. P
Two metallic spheres and are made of the same material and have identical surface finish. The mass of is three times that of . Both the spheres are heated to the same high temperature and placed in the same room having lower temperature but are thermally insulated from each other. The ratio of the initial rate of cooling of to that of is
(1)
(2)
(3)
(4)
The total energy radiated from a black body source is collected for one minute and is used to heat a quantity of water. The temperature of water is found to increase from 20 to 20.5 . If the absolute temperature of the black body is doubled and the experiment is repeated with the same quantity of water at 20, the temperature of water will be
1. 21 2. 22
3. 24 4. 28
A solid sphere and a hollow sphere of the same material and size are heated to the same temperature and allowed to cool in the same surroundings. If the temperature difference between each sphere and its surroundings is same , then
(1) The hollow sphere will cool at a faster rate for all values of T
(2) The solid sphere will cool at a faster rate for all values of T
(3) Both spheres will cool at the same rate for all values of T
(4) Both spheres will cool at the same rate only for small values of T
A solid copper cube of edges 1 cm is suspended in an evacuated enclosure. Its temperature is found to fall from 100 to 99 in 100 s . Another solid copper cube of edges 2 cm, with similar surface nature, is suspended in a similar manner. The time required for this cube to cool from 100 to 99 will be approximately -
(a) 25 s (b) 50 s
(c) 200 s (d) 400 s
A body initially at 80 cools to 64 in 5 minutes and to 52 in 10 minutes. The temperature of the body after 15 minutes will be
(a) 42.7 (b) 35
(c) 47 (d) 40
A hot metallic sphere of radius r radiates heat. It's rate of cooling is
(1) Independent of r
(2) Proportional to r
(3) Proportional to
(4) Proportional to 1/r
A solid copper sphere (density and specific heat capacity c) of radius r at an initial temperature 200K is suspended inside a chamber whose walls are at almost 0K. The time required (in s) for the temperature of the sphere to drop to 100 K is
(1)
(2)
(3)
(4)
A sphere and a cube of same material and same volume are heated upto same temperature and allowed to cool in the same surroundings. The ratio of the amounts of radiations emitted will be
(1) 1 : 1
(2)
(3)
(4)
The graph shown in the adjacent diagram, represents the variation of temperature (T) of two bodies, x and y having same surface area, with time (t) due to the emission of radiation. Find the correct relation between the emissivity (e) and absorptivity (a) of the two bodies .
(1)
(2)
(3)
(4)
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?
1. | 2. | ||
3. | 4. |
Which of the following graphs correctly represents the relation between \(ln~E\) and \(ln~T\) where \(E\) is the amount of radiation emitted per unit time from a unit area of a body and \(T\) is the absolute temperature?\(\left (Take~\sigma =5.67\times 10^{-8} ~W~m^{-2}~K^{-4}~and~0<\epsilon <1 \right )\)
1. | 2. | ||
3. | 4. | Both 1 and 3 |
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°C and allowed to cool in the same environment. The graph that correctly represents their cooling is -