CBSE Class 11 Physics Thermal Properties of Matter Worksheet Set 02

Question. The tempearture of an isolated black body falls from T₁ to T₂ in time t, then t is (Let c be a constant)
(a) t = c(1/T₂ - 1/T₁)
(b) t = c(1/T₂² - 1/T₁²)
(c) t = c(1/T₂³ - 1/T₁³)
(d) t = c(1/T₂⁴ - 1/T₁⁴)

Answer: C

Question. The rate of radiation of a black body at 0ºC is E joule per sec.
Then the rate of radiation of this black body at 273ºc will be
(a) 16 E
(b) 8 E
(c) 4 E
(d) E

Answer: A

Question. The maximum energy in the thermal radiation from a hot source occurs at a wavelength of 11 ×10^–5 cm. According to Wien’s law, the temperature of this source (on Kelvin scale) will be n times the temperature of another source (on Kelvin scale) for which the wavelength at maximum energy is 5.5 × 10^–5 cm. The value n is
(a) 2
(b) 4
(c) 1/2
(d) 1

Answer: C

Question. The temperature of a furnace is 2324ºC and the intensity is maximum in its radiation spectrum nearly at 12000 Å. If the intensity in the spectrum of a star is maximum nearly at 4800Å, then the surface temperature of the star is
(a) 8400ºC
(b) 7200ºC
(c) 6492.5ºK
(d) 5900ºC

Answer: C

Question. spectral energy distribution of the sun (temperature 6050 K) is maximum at 4753 Å. The temperature of a star for which this maximum is at 9506 Å is
(a) 6050 K
(b) 3025 K
(c) 12100 K
(d) 24200 K

Answer: B

Question. According to Newton’s law of cooling, the rate of cooling of a body is proportional to (Dq)n, where Dq is the difference of the temperature of the body and the surroundings, and n is equal to
(a) two
(b) three
(c) four
(d) one

Answer: D

Question. When a body is heated, which colour corresponds to high temperature
(a) red
(b) yellow
(c) white
(d) orange

Answer: C

Question. The two ends of a rod of length L and a uniform crosssectional area A are kept at two temperatures T₁ and T₂ (T₁ > T₂). The rate of heat transfer, dQ/dt through the rod in a steady state is given by
(a) dQ/dt = k (T₁ + T₂)/LA
(b) dQ/dt = kLA(T₁ + T₂)
(c) dQ/dt = kA(T₁ + T₂)/L
(d) dQ/dt = kL(T₁ + T₂)/A

Answer: C

Question. The temperature of an iron block is 140ºF. Its temperature on the Celsius scale is
(a) 60º
(b) 160º
(c) 140º
(d) 132º

Answer: A

Question. A metal cube of length 10.0 mm at 0°C (273K) is heated to 200°C (473K). Given : its coefficient of linear expansion is 2 × 10^–5 K^–1. The percent change of its volume is
(a) 0.1
(b) 0.2
(c) 0.4
(d) 1.2

Answer: D

Question. No other thermometer is suitable as a platinum resistance thermometer to measure temperatures in the entire range of
(a) –50ºC to + 350ºC
(b) –200ºC to + 600ºC
(c) 0ºC to 100ºC
(b) 100ºC to 1500ºC

Answer: B

Question. The fastest mode of transfer of heat is
(a) conduction
(b) convection
(c) radiation
(d) None of these

Answer: C

Question. In order that the heat flows from one part of a solid to another part, what is required?
(a) Uniform density
(b) Temperature gradient
(c) Density gradient
(d) Uniform temperature

Answer: B

Question. Steam is passed into 22 gm of water at 20ºC. The mass of water that will be present when the water acquires a temperatue of 90ºC (Latent heat of steam is 540 cal/g) is
(a) 24.83 gm
(b) 24 gm
(c) 36.6 gm
(d) 30 gm

Answer: A

Question. The top of an insulated cylindrical container is covered by a disc having emissivity 0.6 and conductivity 0.167 WK^–1m^–1 and thickness 1 cm. The temperature is maintained by circulating oil as shown in figure. Find the radiation loss to the surrounding in Jm–2s^–1 if temperature of the upper surface of the disc is 27°C and temperature of the surrounding is 27°C.
(a) 595 Jm^–2s^–1
(b) 545 Jm^–2s^–1
(c) 495 Jm^–2s^–1
(d) None of these

Answer: A

Question. Coefficient of linear expansion of brass and steel rods are α₁ and α₂. Lengths of brass and steel rods are l1and l2 respectively. If (l₂ - l₁) is maintained same at all temperatures, which one of the following relations holds good ? 
(a) α₁l₂₂ =α₂ l₁₂
(b) α₁l₂ =α₂ l₁
(c) α₁l₂ =α₂ l1
(d) α₁l₁ = α₂l₂

Answer: D

Question. A cylindrical rod of aluminium is of length 20 cms and radius 2 cms. The two ends are maintained at temperatures of 0^ºC and 50ºC the coefficient of thermal conductivity is 0.5 cal/cm×sec ׺C . Then the thermal resistance of the rod in cal/sec ׺C is
(a) 318
(b) 31.8
(c) 3.18
(d) 0.318

Answer: D

Question. Two rods P and Q of same length and same diameter having thermal conductivity ratio 2 : 3 joined end to end. If temperature at one end of P is 100°C and at one and of Q 0°C, then the temperature of the interface is
(a) 40°C
(b) 50°C
(c) 60°C
(d) 70°C

Answer: A

Question. 100 g of ice is mixed with 100 g of water at 100ºC. What will be the final temperature of the mixture ?
(a) 13.33ºC
(b) 20ºC
(c) 23.33ºC
(d) 40ºC

Answer: A

Question. The coefficient of apparent expansion of mercury in a glass vessel is 153 × 10^–6/ºC and in a steel vessel is 144 × 10^–6/ºC.
If a for steel is 12 × 10^–6/ºC, then, that of glass is
(a) 9 × 10^–6/ºC
(b) 6 × 10^–6/ºC
(c) 36 × 10^–6/ºC
(d) 27 × 10^–6/ºC

Answer: A

Question. A pendulum clock is 5 seconds fast at temperature of 15ºC and 10 seconds slow at a temperature of 30ºC. At what temperature does it give the correct time? (take time interval = 24 hours)
(a) 18ºC
(b) 20ºC
(c) 22ºC
(d) 25ºC

Answer: C

Question. Two bodies A and B are placed in an evacuated vessel maintained at a temperature of 27ºC. The temperature of A is 327ºC and that of B is 227ºC. The ratio of heat loss from A and B is about
(a) 2 : 1
(b) 1 : 2
(c) 4 : 1
(d) 1 : 4

Answer: A

Question. A beaker contains 200 gm of water. The heat capacity of the beaker is equal to that of 20 gm of water. The initial temperatue of water in the beaker is 20ºC. If 440 gm of hot water at 92ºC is poured in it, the final temperature, neglecting radiation loss, will be nearest to
(a) 58ºC
(b) 68ºC
(c) 73ºC
(d) 78ºC

Answer: B

Question. Steam at 100ºC is passed into 1.1 kg of water contained in a calorimeter of water equivalent 0.02 kg at 15ºC till the temperature of the calorimeter and its contents rises to 80ºC.The mass of the steam condensed in kg is
(a) 0.130
(b) 0.065
(c) 0.260
(d) 0.135

Answer: A

Question. Calculate the surface temperature of the planet, if the energy radiated by unit area in unit time is 5.67 ×104 watt.
(a) 1273°C
(b) 1000°C
(c) 727°C
(d) 727K

Answer: C