THERMAL PROPERTIES OF MATTER QUIZ-19
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.
Q181. The graph AB shown in Fig. is a plot of temperature of a body in degree celsius and degree Fahrenheit. Then
Solution
Q182. The coefficient of linear expansion of an inhomogeneous rod changes linearly from α_1 to α_2 from one end to the other other end of the rod. The effective coefficient of linear expansion of rod is
Solution
Q183. Statement 1: The equivalent thermal conductivity of two plates of same thickness in contact (series) is less than the smaller value of thermal conductivity
Statement 2: For two plates of equal thickness in contact (series) the equivalent thermal conductivity is given by 1/K=1/K_1 +1/K_2
Solution
Q184. Statement 1: A brass tumbler feels much colder than a wooden tray on a chilly day
Statement 2: The thermal conductivity of brass is less than that of wood
Solution
184 (c) The thermal conductivity of brass is high i.e., brass is a good conductor of heat. So, when a brass tumbler is touched, heat quickly flows from human body to tumbler. Consequently, the number appears colder, on the other hand wood is a bad conductor. So, heat does not flow from the human body to the wooden tray in this case. Thus it appears comparatively hotter
184 (c) The thermal conductivity of brass is high i.e., brass is a good conductor of heat. So, when a brass tumbler is touched, heat quickly flows from human body to tumbler. Consequently, the number appears colder, on the other hand wood is a bad conductor. So, heat does not flow from the human body to the wooden tray in this case. Thus it appears comparatively hotter
Q185. Statement 1: Blue star is at high temperature than red star
Statement 2: Wien’s displacement law states that T∝(1/λ_m)
Solution
185 (a) From Wien’s displacement law, temperature (T)∝1/λ_m (where λ_m is the maximum wavelength). Thus temperature of a body is inversely proportional to the wavelength. Since blue star has smaller wavelength and red star has maximum wavelength, therefore blue star is at higher temperature then red star
185 (a) From Wien’s displacement law, temperature (T)∝1/λ_m (where λ_m is the maximum wavelength). Thus temperature of a body is inversely proportional to the wavelength. Since blue star has smaller wavelength and red star has maximum wavelength, therefore blue star is at higher temperature then red star
Q186. Statement 1: A beaker is completely filled with water at 4℃. It will overflow, both when heated or cooled
Statement 2: There is expansion of water below and above 4℃.
Solution
186 (a) Water has maximum density at 4℃. On heating above 4℃, density of water decreases and its volume increases. Therefore, water overflows in both the cases
186 (a) Water has maximum density at 4℃. On heating above 4℃, density of water decreases and its volume increases. Therefore, water overflows in both the cases
Q187. Statement 1: Temperatures near the sea coast are moderate
Statement 2: Water has a high thermal conductivity
Solution
187 (b) During the day when water is cooler than the land, the wind blows off the water onto the land (as warm air rises and cooler air fills the place). Also at night, the effect is reversed (since the water is usually warmer than the surrounding air on land). Due to this wind flow the temperature near the sea coast remains moderate
187 (b) During the day when water is cooler than the land, the wind blows off the water onto the land (as warm air rises and cooler air fills the place). Also at night, the effect is reversed (since the water is usually warmer than the surrounding air on land). Due to this wind flow the temperature near the sea coast remains moderate
Q188. Statement 1: The melting point of ice decreases with increase of pressure
Statement 2: Ice contracts on melting
Solution
188 (a) With rise in pressure melting point of ice decreases. Also ice contracts on melting
188 (a) With rise in pressure melting point of ice decreases. Also ice contracts on melting
Q189. Statement 1: It is hotter over the top of a fire than at the same distance on the sides
Statement 2: Air surrounding the fire conducts more heat upwards
Solution
189 (c) Heat is carried away from a fire sideways mainly by radiations. Above the fire, heat is carried by both radiation and by convection of air. The latter process carries much more heat
189 (c) Heat is carried away from a fire sideways mainly by radiations. Above the fire, heat is carried by both radiation and by convection of air. The latter process carries much more heat
Q190. Statement 1: The thermal resistance of a multiple layer is equal to the sum of the thermal resistance of the individual laminas
Statement 2: Heat transferred is directly proportional to the temperature gradient in each layer
Solution
190 (d) The correct reason is because under steady-state condition, when temperature becomes constant, the rate of conduction of heat across every lamina is the same
190 (d) The correct reason is because under steady-state condition, when temperature becomes constant, the rate of conduction of heat across every lamina is the same
