1. Do all hot objects radiate light? If hot water is placed in a vacuum in total darkness will it radiate heat?Recall that heat is detected through night-vision goggles. These devices "see" infra-red light emitted byhot objects. This is evidence that heat is a part of the spectrum and therefore it can travel through avacuum just as the other components of light. If so, then heat should travel as fast as light through avacuum. It should travel just as fast through air. Why then does the air gap inside the thermos bottle retardthe loss of heat from the hot water inside?2. The coefficient of linear expansion of aluminum is 0.000023/C. An aluminum rod 5 meters long isheated so that its temperature rises from 25 °C to 50 °C. What is the change in its length?3. A rectangular block of concrete has a volume of 5 cubic meters and initial temperature of 30°C. By howmuch will it expand if the temperature rises by 5 C°? The coefficient of thermal expansion of concrete is10/C.4. Cylindrical bars of steel and brass with the same diameter and length are joined at one end. Thetenperature of the steel bar is 350 K; brass, 500 K. What is the temperature at the junction? The thermalconductivity of steel is 45 W/mol K; brass, 116.

If consider light as visible region, then all heated object can not radiate light, but it can…

Do all hot objects radiate light? If hot water is placed in a vacuum in total darkness will it radiate heat? Recall that heat is detected through night-vision goggles. These devices “see" infra-red light emitted by hot objects. This is evidence that heat is a part of the spectrum and therefore it can travel through a vacuum just as the other components of light. If so, then heat should travel as fast as light through a vacuum. It should travel just as fast through air. Why then does the air gap inside the thermos bottle retard the loss of heat from the hot water inside?

Do all hot objects radiate light? If hot water is placed in a vacuum in total darkness will it radiate heat? Recall that heat is detected through night-vision goggles. These devices “see" infra-red light emitted by hot objects. This is evidence that heat is a part of the spectrum and therefore it can travel through a vacuum just as the other components of light. If so, then heat should travel as fast as light through a vacuum. It should travel just as fast through air. Why then does the air gap inside the thermos bottle retard the loss of heat from the hot water inside?