11. The emissivity e of object B is , that of object A, although bothobjects are identical in size and shape. If the objects radiate the sameenergy per second, what is the ratio Tg/T, of their Kelvin temperatures?(a) ㅎ (b) { (e) (d) 2 (e) 4

emissivity of B 1/16 of emissivity of A

Answered: 11. The emissivity e of object B is ,…

College Physics

10th Edition

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Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter10: Thermal Physics

Section: Chapter Questions

Problem 7WUE: One way to cool a gas is to let it expand. When a certain gas under a pressure of 5.00 106 Ha at...

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An aluminum rod 0.500 m in length and with a cross sectional area of 2.50 cm2 is inserted into a thermally insulated vessel containing liquid helium at 4.20 K. The rod is initially at 3(H) K. (a) If one-halt of the rod is inserted into the helium, how many liters of helium boil off by the time the inserted half cools to 4.20 K? Assume the upper half does not yet cool, (b) If the circular surface of the upper end of the rod is maintained at 300 K. what is the approximate boil-off rate of liquid helium in liters per second after the lower half has reached 4.20 K? (Aluminum has thermal conductivity of 3 100 YV/m K at 4.20 K; ignore its temperature variation. The density of liquid helium is 125 kg/m3.)
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Stars A and B have the same temperature, but star A has twice the radius of star B. (a) What is the ratio of star As power output to star Bs output due to electromagnetic radiation? The emissivity of both stars can be assumed to be 1. (b) Repeat the question if the stars have the same radius, but star A has twice the absolute temperature of star B. (c) Whats the ratio if star A has both twice the radius and twice the absolute temperature of star B?
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11. The emissivity e of object B is , that of object A, although both objects are identical in size and shape. If the objects radiate the same energy per second, what is the ratio Tg/T, of their Kelvin temperatures? (a) ㅎ (b) { (e) (d) 2 (e) 4