Q.1
The ends of two rods of different materials with their thermal conductivities, radii of cross-sections and lengths all are in ratio 1 : 2 are maintained at the same temperature difference. If the rate of flow of heat in the larger rod is 4 cal/sec, then in the shorter rod in cal/sec will be [ EAMCET 1986]
  • a) 1
  • b) 2
  • c) 8
  • d) 16
Q.2
A cylindrical rod with one in a steam chamber and the other end in ice results in melting of 0.1gm of ice per second. If the rod is replaced by another with half the length and double the radius of the first and if the thermal conductivity of material of second rod is (1/4) that of first, the rate at which ice melts in gm/sec will be [ EAMCET 1987]
  • a)3.2
  • b) 1.6
  • c)0.2
  • d)0.1
Q.3
Two spheres of different materials, one with double the radius and one-fourth wall thickness of the other, are filled with ice. If the time taken for complete melting of ice in the larger radius one is 25 minutes and that for smaller one in 16 minutes, the ratio of thermal conductivities of the materials of larger sphere to the smaller sphere is [ EAMCET 1991]
  • a) 4 : 5
  • b) 5 : 4
  • c)25 : 8
  • d)8 : 25
Q.4
One end of a copper rod of length 1.0m and area of cross-section 10-3 m2 is immersed in boiling water and the other end in ice. If the coefficient of thermal conductivity of copper is 92 cal/m/s/°C and the latent heat of ice is 8×104 cal/kg, then the amount of ice which will melt in one minute is [ MNR 1994]
  • a) 9.2 × 10⁻³ kg
  • b) 8 × 10⁻³ kg
  • c) 6.9 × 10⁻³ kg
  • d) 5.4 × 10⁻³ kg
Q.5
Which of the following statement is wrong [ MPPMT 1993]
  • a) Stefan's constant is the same for all black bodies
  • b) Thermal radiations travel with the speed of 3×108 m/s
  • c) Thermal radiations exhibits diffraction
  • d) Stefan's law is applicable for all heated bodies
Q.6
A sphere, a cube and a thin circular plate all made of the same material and having the same mass are heated to the same temperature of 200°C when these are left in room [ MPPMT 1993]
  • a) the sphere reaches room temperature last
  • b) the cube reaches room temperature last
  • c) the circular plate reaches room temperature last
  • d) all will reach the room temperature simultaneously
Q.7
A piece of metal and a piece of wood are kept in a room at room temperature which is 45°C. On touching the two with hand [ MPPET 1993]
  • a) the two will appear equally hot
  • b) the piece of wood will appear hotter than the piece of metal
  • c) the piece of metal will appear hotter than the piece of wood
  • d) the distinction in the hotness will not be possible
Q.8
An electric heater, kept in vacuum is heated continuously by passing electric current. Its temperature will [ MPPMT 1993]
  • a) go on rising with time
  • b) stop rising after some time as it will lose heat to the surrounding by conduction
  • c) will rise for some time and thereafter will start falling
  • d) will become constant after some time due to loss of heat by radiation
Q.9
At specific temperature, the energy densities for black body for three different wavelengths are 10,19 and 7 units. For these wavelengths if the absorption coefficient of a body is respectively 0.8, 0.3 and 0.9, then the emissive power of this body for these wave-lengths are in the ratio
  • a) 10 : 19 : 7
  • b) 8 : 3 : 9
  • c) 8 : 5.7 : 6.3
  • d) 8 : 95 : 4.3
Q.10
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 [ CPMT 1989]
  • a) the temperature of A is maximum, B is minimum and C is intermediate
  • b) the temperature of A is maximum, C is minimum and B is intermediate
  • c) the temperature of B is maximum, A is minimum and C is intermediate
  • d) the temperature of C is maximum, B is minimum and A is intermediate
Q.11
A blackened metal foil is warmed by radiation from a point source whose temperature is T and distance from the foil is d. It is found that the power received from the foil is P. If both the temperature and distance are doubled, the power received by the foil will be [ MPPMT 1997]
  • a) P
  • b) 2P
  • c) 4P
  • d) 16P
Q.12
Three rods of identical area of cross-section and made from the same metal, from the sides of an isosceles triangle ABC, right-angled at B. The points A and B are maintained at temperature T and (√2) T, respectively. in the steady state, the temperature of the part C is Tc. Assuming that only heat conduction takes place Tc / T is [ IIT 1995]
  • a)
    ch-8_qn-239choice_img_no1.png
  • b)
    ch-8_qn-239choice_img_no2.png
  • c)
    ch-8_qn-239choice_img_no3.png
  • d)
    ch-8_qn-239choice_img_no4.png
Q.13
If the colour of star is changing from red to blue it means [ RajPMT 1996]
  • a) The star is going away from the earth
  • b) The star is coming near the earth
  • c) The star is stationary
  • d) Non of the above
Q.14
If a liquid is heated in space under no gravity , the transfer of heat will take place by process of [ Raj.PMT 1996]
  • a) conduction
  • b) convection
  • c) Radiation
  • d) Cannot be heated in absence of gravity
Q.15
A body radiates energy 5W at temperature of 127°. If the temperature is increased to 927 °C then it radiates energy at the rate of [ BHU 1995]
  • a) 410 W
  • b) 81 W
  • c) 405 W
  • d) 200W
Q.16
If the temperature of sun is doubled [ raj. PMT 1996]
  • a) Emission will become four times
  • b) Emission will become double
  • c) Mainly it will emit ultra violet radiations
  • d) Mainly it will emit infra red radiations
Q.17
Two rods of same length and material transfers given amount of heat in 12 sec, when they are joined end to end. But when they are joined lengthwise, then they will transfer same heat in same conditions in [ BHU 1998]
  • a) 24 sec
  • b) 3 sec
  • c) 1.5 sec
  • d) 48 sec
Q.18
A metal ball immersed in alcohol weighs W1 at 0°C and W2 at 95°C. the coefficient of cubical expansion of the metal is less than that of alcohol. Assuming that the density of the metal is large compared to that of alcohol, it can be shown that [ CPMT 1998]
  • a) W1 > W2
  • c) W1 < W2
  • b) W₁ = W₂
  • d) W₂ = W₁ /2
Q.19
Two rods of lengths l1 and l2 are made of materials whose coefficients of linear expansions are α1 and αIf the difference between the two lengths is independent of temperature [ EAMCET 1995]
  • a)
    ch-8_qn-248choice_img_no1.png
  • b)
    ch-8_qn-248choice_img_no2.png
  • c)
    ch-8_qn-248choice_img_no3.png
  • d)
    ch-8_qn-248choice_img_no4.png
Q.20
The temperature of an isotropic cubical solid of length L, density d and coefficient of expansion α per degree Kelvin, is raised by 10°C. Then, at this temperature, to a good approximation ..[ IIT 1995]
  • a) Lengt is L(1 +10α)
  • b) Total surface area is L2 ( 1 +20α)
  • c) density is d (1 + 30α)
  • d) density is d/(1+30α)
Q.21
A ring shaped piece of metal is heated . If the material expands, the hole will [ EAMCET 1994]
  • a) expand
  • b) contract
  • c) expand or contracts depending on the width of ring
  • d) expand or contract depending on the value of the coefficient of expansion
Q.22
A beaker is filled with water at 4°C. At one time the temperature is increased by few degrees above 4°C and at another time it is decreased by few degree below 4°C. One shall observe that
  • a) the level remains constant in each case
  • b) water overflows in both cases
  • c) water overflows in the latter case, while its level comes down in the previous case
  • d) in previous case water overflows while in latter case its level comes down
Q.23
A container of volume 1 m3 is divided into two equal compartments by a partition. One of these compartments contains an ideal gas at 300K. The other compartment is vacuum. The whole system is thermally isolated from its surroundings. The partition is removed and gas expands to occupy the whole volume of the container. It temperature now would be ..[ UGET 1995]
  • a) 300 K
  • b) 250K
  • c) 200 K
  • d) 100 K
Q.24
A long cylindrical vessel of volume V and linear coefficient of expansion α contains a liquid. The level of liquid has not changed then coefficient of cubical expansion of liquid is .. [ EAMCET 1986]
  • a) (V -α) / V
  • b) (V + α) / V
  • c) V / (V -α)
  • d) 3α
Q.25
A bimetallic strip having two strips each of thickness 'd' are heated by Δt°C. If their coefficient of linear expansions are α1 and α2 respectively, then on heating they will bend in the form of arc whose radius is
  • a)
    ch-8_qn-257choice_img_no1.png
  • b)
    ch-8_qn-257choice_img_no2.png
  • c)
    ch-8_qn-257choice_img_no3.png
  • d)
    ch-8_qn-257choice_img_no4.png
Q.26
The moment of inertia of an object is l and the coefficient of linear expansion is α. If the temperature of the object is changed by Δθ , then the change in its moment of inertia is
  • a) αlΔθ
  • b) 2αlΔθ
  • c)4αlΔθ
  • d)αlΔθ/2
Q.27
A sphere of density ρ, specific heat capacity c and radius r, is hung by a thermally insulated thread in an enclosure which is kept at lower temperature than the sphere. the temperature of the sphere starts to drop at the rate which depends up on the temperature difference between the sphere and the enclosure and the nature of the surface of the sphere and is proportional to ..
  • a) c/ r3ρ
  • b) 1 / r3ρc
  • c) 3r3ρc
  • d) 1 / rρc
Q.28
The following four wires are made of the samematerial. Which of these will have the largestextension when the same tension is applied?
  • a) Length = 50 cm, diameter = 0.5 mm
  • b) Length = 100 cm, diameter = 1 mm
  • c) Length = 200 cm, diameter = 2 mm
  • d) Length = 300 cm, diameter = 3 mm
Q.29
The wettability of a surface by a liquid dependsprimarily on
  • a) Viscosity
  • b) Surface tension
  • c) Density
  • d) Angle of contact between the surface and theliquid
Q.30
Copper of fixed volume 'V' is drawn intowireof length 'L '.When thiswire is subjected to aconstant force 'F', the extension produced in the wire in 'ΔL '.Which of the following graphsis a straight line?[ AIMPT 2014]
  • a) ΔL versus 1/L2
  • b) ΔL versus L
  • c) ΔL versus 1/L
  • d) ΔL versus L2
0 h : 0 m : 1 s