THERMAL PROPERTIES OF MATTER QUIZ-21
Dear Readers,
JEE Advanced Physics Syllabus can be referred by the IIT aspirants to get a detailed list of all topics that are important in cracking the entrance examination. JEE Advanced syllabus for Physics has been designed in such a way that it offers very practical and application-based learning to further make it easier for students to understand every concept or topic by correlating it with day-to-day experiences. In comparison to the other two subjects, the syllabus of JEE Advanced for physics is developed in such a way so as to test the deep understanding and application of concepts.
Q201. Statement 1: In thermal conduction, energy is transferred due to chaotic motion of conduction electron and atomic vibrations from region of high temperature to low temperature
Statement 2: There is overall transference of particles of conducting body
Solution
201(c) There is only energy transfer and not matter transfer
201(c) There is only energy transfer and not matter transfer
Q202. Statement 1: Radiation is the speediest mode of heat transfer
Statement 2: Radiation can be transmitted in zig-zag motion
Solution
202(c) Actually, the process of radiation does not require any material for transmission of heat Thermal radiation travels with the velocity of light and hence the fastest mode of the transfer. Thermal radiation is always transmitted in a straight line
202(c) Actually, the process of radiation does not require any material for transmission of heat Thermal radiation travels with the velocity of light and hence the fastest mode of the transfer. Thermal radiation is always transmitted in a straight line
Q203. Statement 1: In natural convection, the fluid motion is caused due to density difference produced by temperature gradient
Statement 2: In forced convection, the fluid is forced to flow along the solid surface by means of fans or pumps
Solution
203(b) Statement I and II are true but Statement II is not correct explanation for Statement I
203(b) Statement I and II are true but Statement II is not correct explanation for Statement I
Q204. Statement 1: Fahrenheit is the smallest unit measuring temperature
Statement 2: Fahrenheit was the first temperature scale used for measuring temperature
Solution
204 (c) Celsius scale was the first temperature scale and Fahrenheit is the smallest unit measuring temperature
204 (c) Celsius scale was the first temperature scale and Fahrenheit is the smallest unit measuring temperature
Q205. Statement 1: The radiation from the sun’s surface varies as the fourth power of its absolute temperature
Statement 2: The sun is not a black body
Solution
205 (c) At a high temperature (6000 K), the sun acts like a perfect blackbody emitting complete radiation. That’s why the radiation coming from the sun’s surface follows Stefan’s law E=σT4
205 (c) At a high temperature (6000 K), the sun acts like a perfect blackbody emitting complete radiation. That’s why the radiation coming from the sun’s surface follows Stefan’s law E=σT4
Q206. Statement 1: For higher temperature, the peak emission wavelength of a black body shifts to lower wavelength
Statement 2: Peak emission wavelength of a blackbody is proportional to the fourth power of temperature
Solution
206 (c) According to Wien’s law λ_m T= constant i.e., peak emission wavelength λ_m∝1/T. Also as T increases λ_m decreases. Hence assertion is true but reason is false
206 (c) According to Wien’s law λ_m T= constant i.e., peak emission wavelength λ_m∝1/T. Also as T increases λ_m decreases. Hence assertion is true but reason is false
Q207. Statement 1: Animals curl into a ball, when they feel very cold
Statement 2: Animals by curling their body reduce the surface area
Solution
207 (a) When the animals feel cold, they curl their bodies into a ball so as to decrease the surface area of their bodies. As total energy radiated by body varies directly as the surface area of the body, the loss of heat due to radiation would be reduced
207 (a) When the animals feel cold, they curl their bodies into a ball so as to decrease the surface area of their bodies. As total energy radiated by body varies directly as the surface area of the body, the loss of heat due to radiation would be reduced
Q208. Statement 1: Woolen clothes keep the body warm in winter
Statement 2: Air is a bad conductor of heat
Solution
208(a) Woolen fibres enclose a large amount of air in them. Both wool and air are the bad conductors of heat and the coefficient of thermal conductivity is small. So, they prevent any loss of heat from our body
208(a) Woolen fibres enclose a large amount of air in them. Both wool and air are the bad conductors of heat and the coefficient of thermal conductivity is small. So, they prevent any loss of heat from our body
Q209. Statement 1: Snow is better insulator than ice
Statement 2: Snow contains air packet and air is good insulator of heat
Solution
209 (a) When the temperature of the atmosphere reaches below 0℃, then the water vapours present in air, instead of condensing, freeze directly in the form of minute particles of ice. Many particles coalesce and take cotton-like shape which is called snow. Thus snow contains air packets in which convection currents cannot be formed. Hence snow is a good heat insulator. In ice there is no air, so it is a bad insulator
209 (a) When the temperature of the atmosphere reaches below 0℃, then the water vapours present in air, instead of condensing, freeze directly in the form of minute particles of ice. Many particles coalesce and take cotton-like shape which is called snow. Thus snow contains air packets in which convection currents cannot be formed. Hence snow is a good heat insulator. In ice there is no air, so it is a bad insulator
Q210. Statement 1: Two bodies at different temperatures, if brought in thermal contact do not necessary settle to the mean temperature
Statement 2: The two bodies may have different thermal capacities
Solution
210 (a) When two bodies at temperature T_1 and T_2 are brought in thermal contract, they do settle to the mean temperature (T_1+T_2)/2. They will do so, in case the two bodies were of same mass and material, i.e., same thermal capacities. In other words, the two bodies may be having different thermal capacities, that’s why they do not settle to the mean temperature, when brought together
210 (a) When two bodies at temperature T_1 and T_2 are brought in thermal contract, they do settle to the mean temperature (T_1+T_2)/2. They will do so, in case the two bodies were of same mass and material, i.e., same thermal capacities. In other words, the two bodies may be having different thermal capacities, that’s why they do not settle to the mean temperature, when brought together
