CBSE Class 11 Physics Thermal Properties of Matter Worksheet Set A

Question. Solar radiation emitted by sun resembles that emitted by a black body at a temperature of 6000 K. Maximum intensity is emitted at wavelength of about 4800 Å. If the sun were to cool down from 6000 K to 3000 K, then the peak intensity would occur at a wavelength
(a) 4800 Å
(b) 9600 Å
(c) 2400 Å
(d) 19200 Å

Answer: B

Question. For the construction of a thermometer, one of the essential requirements is a thermometric substance which
(a) remains liquid over the entire range of temperatures to be meaured .
(b) has property that varies linearly with temperature
(c) has a property that varies with temperature
(d) obey Boyle's law

Answer: C

Question. The coefficient of thermal conductivity depends upon
(a) temperature difference between the two surfaces.
(b) area of the plate
(c) material of the plate
(d) All of these

Answer: C

Question. The sprinkling of water slightly reduces the temperature of a closed room because
(a) temperature of water is less than that of the room
(b) specific heat of water is high
(c) water has large latent heat of vaporisation
(d) water is a bad conductor of heat

Answer: C

Question. If a bar is made of copper whose coefficient of linear expansion is one and a half times that of iron, the ratio of force developed in the copper bar to the iron bar of identical lengths and cross-sections, when heated through the same temperature range (Young’s modulus of copper may be taken to be equal to that of iron) is
(a) 3/2
(b) 2/3
(c) 9/4
(d) 4/9

Answer: A

Question. The wavelength of radiation emitted by a body depends upon
(a) the nature of its surface
(b) the area of its surface
(c) the temperature of its surface
(d) All of the above

Answer: D

Question. A vessel completely filled with a liquid is heated. If α and γ represent coefficient of linear expansion of material of vessel and coefficient of cubical expansion of liquid respectively, then the liquid will not overflow if
(a) γ = 3 α
(b) γ > 3 α
(c) γ < 3 α
(d) γ ≤ 3 α

Answer: D

Question. A mountain climber finds that water boils at 80ºC. The temperature of this boiling water is...... Fahrenheit
(a) 50º
(b) 150º
(c) 176º
(d) 200º

Answer: C

Question. A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be :
(a) 450
(b) 1000 
(c) 1800
(d) 225

Answer: C

Question. Two straight metallic strips each of thickness t and length l are rivetted together. Their coefficients of linear expansions are α₁ and α₂ . If they are heated through temperature DT, the bimetallic strip will bend to form an arc of radius
(a) t /{α₁ + α₂)ΔT}
(b) t /{(α₂ - α₁)ΔT}
(c) t (α₁ - α₂)ΔT
(d) t (α₂ - α₁)ΔT

Answer: B

Question. Two solid spheres, of radii R₁ and R₂ are made of the same material and have similar surfaces. The spheres are raised to the same temperature and then allowed to cool under identical conditions. Assuming spheres to be perfect conductors of heat, their initial rates of loss of heat are
(a) R₁²/R₂²
(b) R₁ / R₂
(c) R₂ / R₁
(d) R₂²/R₁²

Answer: A

Question. A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transferred to the surface is
(a) Ec
(b) 2E/c
(c) E/c
(d) E/c²

Answer: B

Question. Which of the following graph correctly represents the relation between ln E and lnT where E is the amount of radiation emitted per unit time from unit area of body and T is the absolute temperature 

Answer: C

Question. The temperature of the Sun is measured with
(a) platinum thermometer
(b) gas thermometer
(c) pyrometer
(d) vapour pressure thermometer.

Answer: C

Question. Which of the following circular rods, (given radius r and length l) each made of the same material and whose ends are maintained at the same temperature will conduct most heat?
(a) r = 2r₀; l = 2l₀
(b) r = 2r₀; l = l₀
(c) r = r₀; l = 2l₀
(d) r = r₀; l = l₀

Answer: B

Question. At a certain temperature for given wave length , the ratio of emissive power of a body to emissive power of black body in same circumstances is known as
(a) relative emissivity
(b) emissivity
(c) absorption coefficient
(d) coefficient of reflection

Answer: C

Question. If a liquid is heated in weightlessness, the heat is transmitted through
(a) conduction
(b) convection
(c) radiation
(d) None of these, because the liquid cannot be heated in weightlessness.

Answer: A

Question. 540 g of ice at 0°C is mixed with 540 g of water at 80°C. The final temperature of mixture is
(a) 0°C
(b) 40°C
(c) 80°C
(d) less than 0°C

Answer: A

Question. Which of the following is not close to a black body?
(a) Black board paint
(b) Green leaves
(c) Black holes
(d) Red roses

Answer: A

Question. Two rods of the same length and areas of cross-section A₁ and A₂ have their ends at the same temperature. K₁ and K₂ are the thremal conductivities of the two rods. The rate of flow of heat is same in both rods if
(a) A₁/A₂ = K₁/K₂
(b) A₁/A₂ = K₂/K₁
(c) A₁A₂ = K₁K₂
(d) A₁ K₁² = A₂K₂²

Answer: B

Question. The resistance of a resistance thermometer has values 2.71 and 3.70 ohms at 10ºC and 100ºC respectively. The temperature at which the resistance is 3.26 ohm is
(a) 40ºC
(b) 50ºC
(c) 60ºC
(d) 70ºC

Answer: C

Question. The temperature of stars is determined by
(a) Stefan’s law
(b) Wien’s displacement law
(c) Kirchhoff’s law
(d) Ohm’s law

Answer: B

Question. A metal ball of surface area 200 square cm, temperature 527ºC is surrounded by a vessel at 27ºC. If the emissivity of the metal is 0.4, then the rate of loss of heat from the ball is approximately σ = 5.67 x 10^-8 joule/m² x sec x K²
(a) 108 joule
(b) 168 joule
(c) 182 joule
(d) 192 joule

Answer: C

Question. A metallic rod l cm long, A square cm in cross-section is heated through tºC. If Young’s modulus of elasticity of the metal is E and the mean coefficient of linear expansion is a per degree celsius, then the compressional force required to prevent the rod from expanding along its length is
(a) E A α t
(b) E A α t/(1 + αt)
(c) E A α t/(1 – α t)
(d) E l α t

Answer: A

Question. A black body rediates energy at the rate of E watt per metre² at a high temperature T K. when the temperature is reduced to (T/2) K, the radiant energy will be
(a) E/16
(b) E/4
(c) E/2
(d) 2E

Answer: A