Q.1
A cylinder of radius R made of a material of thermal conductivity $K_1$ is surrounded by a cylindrical shell of inner radius R and outer radius 2R made of material of thermal conductivity $K_2$ . The two ends of the combined system are maintained at two different temperatures. There is no loss of heat across the cylindrical surface and the system is in steady state. The effective thermal conductivity of the system is
  • $K_1+K_2$
  • $\frac {K_1 K_2}{K_1+ K_2 }$
  • $(K_1+ 3K_2)/4$
  • $(3K_1+K_2)/4 $
Q.2
If mass-energy equivalence is taken into account, when water is cooled to from ice, the mass of water should
  • increase
  • remain unchanged
  • decrease
  • first increase then decrease
Q.3
A black body is at a temperature of 2880 K. The energy of radiation emitted by this body with wavelength between 499 nm and 500 nm is $U_1$, between 999 nm and 1000 nm is $U_2$and between 1499 nm and 1500 nm is $U_3$.[The Wien constant, $b = 2.88 \times 10^6 nm K%].Then
  • $U_1 = 0$
  • $U_3 =0$
  • $U_1 > U_2$
  • $U_1 < U_2$
Q.4
A metal rod of young's modulus Y and coefficient of thermal expansion α is held at its two ends such that its length remains invariant. If its temperature is raised by t°C, the linear stress developed in it is
  • $ \frac {\alpha t}{Y}$
  • $\frac {Y}{\alpha t }$
  • $Y \alpha t$
  • $\frac {1}{Y \alpha t}$
Q.5
Two spherical stars A and B emit blackbody radiation. The radius of A is 400 times that of B and A emits $10^4$ times the power emitted from B. The ratio $ \frac {\lambda _A}{\lambda _B}$ of their wavelengths at which the peaks occur in their respective radiation curves is
  • 2 :1
  • 1 : 2
  • 3 :1
  • 4 :1
Q.6
A wooden wheel of radius R is made of two semicircular parts(see figure). The two parts are field together by a ring made of a metal strip of cross-sectional area S and length L. L is slightly less than $2 \pi R$. To fit the ring on the wheel, it is heated so that its temperature rises by $\Delta T$ and it just steps over the wheel. As it cools down to the surrounding temperature, it presses the semicircular parts together. If the coefficient of linear expansion of the metal is $\alpha$ and its Young's modulus is Y, the force that one part of the wheel applies on the other part is?
thermal-properties-of-matter-jee-mcq.png
  • $SY \alpha \Delta T$
  • $ \pi SY \alpha \Delta T$
  • $2SY \alpha \Delta T$
  • $ 2 \pi SY \alpha \Delta T$
Q.7
If the temperature of the sun were to increase from T to 2T and its radius from R to 2R, then the ratio of the radiant energy received on earth to what it was previously will be
  • 4
  • 16
  • 32
  • 64
Q.8
As the temperature is increased, the time period of a pendulum
  • increases as its effective length increases even though its centre of mass still remains at the centre of the bob.
  • decreases as its effective length increases even though its centre of mass still remains at the centre of the bob.
  • increases as its effective length increases due to shifting of centre of mass below the centre of the bob.
  • decreases as its effective length remains same but the centre of mass shifts above the centre of the bob.
Q.9
the increase in moment of inertia I of a uniform rod (coefficient of linear expansion $\alpha$ ) about its perpendicular bisector when its temperature is slightly increased by $\Delta T$ is
  • $ \frac {I \alpha \Delta}{2}$
  • $ I \alpha \Delta$
  • $4 I \alpha \Delta$
  • $2 I \alpha \Delta$
Q.10
Two conductors having same width and length, thickness d1 and d2 , thermal conductivity k1 and k2 are placed one above the another. Find the equivalent thermal conductivity
  • $ \frac { (d_1 + d_2)(k_1 d_2 + k_2 d_1)}{2(k_1 + k_2)}$
  • $ \frac { (d_1 - d_2)(k_1 d_2 + k_2 d_1)}{2(k_1 + k_2)}$
  • $ \frac { ((k_1 d_2 + k_2 d_1)}{(d_1 + d_2)}$
  • $ \frac { ((k_1 + k_2 )}{(d_1 + d_2)}$
Q.11
In the following questions, a statement of assertion is  followed by a statement of reason. You are required to  choose the correct one out of the given four responses and  mark it as (a) If both assertion and reason are true and reason is  the correct explanation of the assertion. (b) If both assertion and reason are true but reason is  not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false Assertion: The melting point of ice decreases with increase of pressure. Reason: Ice contracts on melting.
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
Q.12
In the following questions, a statement of assertion is  followed by a statement of reason. You are required to  choose the correct one out of the given four responses and  mark it as (a) If both assertion and reason are true and reason is  the correct explanation of the assertion. (b) If both assertion and reason are true but reason is  not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false Assertion: A tube light emits white light. Reason: Emission of light in a tube takes place at a very high temperature
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
Q.13
In the following questions, a statement of assertion is  followed by a statement of reason. You are required to  choose the correct one out of the given four responses and  mark it as (a) If both assertion and reason are true and reason is  the correct explanation of the assertion. (b) If both assertion and reason are true but reason is  not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false Assertion: At room temperature water does not sublimate from ice to steam. Reason: The critical point of water is much above the room temperature.
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
Q.14
In the following questions, a statement of assertion is  followed by a statement of reason. You are required to  choose the correct one out of the given four responses and  mark it as (a) If both assertion and reason are true and reason is  the correct explanation of the assertion. (b) If both assertion and reason are true but reason is  not correct explanation of the assertion. (c) If assertion is true, but reason is false. (d) If both assertion and reason are false. (e) If reason is true but assertion is false Assertion: Temperatures near the sea coast are moderate. Reason: Water has high thermal conductivity
  • (a)
  • (b)
  • (c)
  • (d)
  • (e)
Q.15
The top of an insulated cylindrical container is covered by a disc having radiation emissivity 0.6, thermal conductivity 0.167 $W m^{-1} k^{-1}$ and thickness 1 cm. The temperature is maintained by circulating oil as shown in the figure. The temperature of the upper surface of disc is 127 °C and temperature of the surrounding is 27°C. Neglect the heat loss due to convection. [Given $\sigma\=\frac{17}{3} \tims 10^{-8} Wm^{-2} K^{-4}$ ] Find the rate of radiation loss to the surroundings by unit area of the disc
thermal-properties-of-matter-jee-mcq-2.png
  • 550 W/m2
  • 595 W/m2
  • 600 W/m2
  • 650 W/m2
Q.16
Find the temperature of the circulating oil
  • 150 °C
  • 172 ° C
  • 162.6 °C
  • none of these
Q.17
Calorie is defined as the amount of heat required to raise the temperature of 1 g of water by 1 °C and it is defined under which of the following conditions?
  • From 14.5 °C to 15.5 °C at 760 mm of Hg
  • From 98.5°C to 99.5 °C at 760 mm of Hg
  • From 13.5° C to 14.5° C at 76 mm of Hg
  • From 3.5 ° C to 4.5° C at 76 mm of Hg
Q.18
Temperature of the star is determined by
  • distance
  • colour
  • size
  • None of these
Q.19
Planck's constant has dimensions
  • $[ML^2 T^{-1} ]$
  • $[ML T^{-1} ]$
  • $[ML^2 T^{-2} ]$
  • $[ML^2 T^1 ]$
Q.20
Parallel rays of light of intensity $I=912 W/m^2$ are incident on a spherical black body kept in surroundings of temperature 300 K. Take Stefan-Boltzmann constant $\sigma = 5.7 \times 10^{-8} W^{-2} mK^{-4}$ and assume that the energy exchange with the surroundings is only through radiation. The final steady state temperature of the black body is close to
  • 330 K
  • 660 K
  • 990 K
  • 1500 K
0 h : 0 m : 1 s