Radiation: The radius of a star is 6.95 × 108 m, and its rate of radiation has been measured to be 5.32 × 1026 W. Assuming that it is a perfect emitter, what is the temperature of the surface of this star? (? = 5.67 × 10-8 W/m2 ? K4)
A. 6.27 × 103 K
B. 8.25 × 103 K
C. 8.87 × 103 K
D. 3.93 × 107 K
E. 5.78 × 107 K
Answer: A
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If two stars have a magnitude difference of 5, what is their flux ratio?
a. 10.0 b. 12.6 c. 100.0 d. 250.0 e. 625.3
X-Ray Diffraction: A researcher is using x-rays to investigating a cubic crystal. He is looking at Bragg reflection from the planes parallel to the cube faces. He finds that when using x-rays with a wavelength of 0.165 nm, a strong first maximum occurs when the beam makes an angle of 23.5° with the planes. What is the spacing of adjacent atoms in this crystal?
Fill in the blank(s) with the appropriate word(s).
In order to conserve energy, the inner surface of double-glazed windows are treated with a low emissivity coating that reduces the emissivity of the uncoated surface from 0.95 to 0.5 for the coated surface. If the temperatures of the two glass panes are 20°C and 0°C, respectively, determine the reduction in heat transfer in a coated double-glazed window as compared with the uncoated one.
GIVEN
? Double glazed windows treated with low emissivity coating that reduce emissivity of uncoated
surface from ??1 =0.95 to ??2= 0.5.
? Temperature of glass pane 1 (T1)= 20°C = 293 K
? Temperature of glass plane 2 (T2) = 0°C = 273
FIND
Reduction in heat transfer in coated double glazed window as compared to uncoated one.
PROPERTIES AND CONSTANTS
From Appendix 1, Table 5, the Stephan-Boltzmann constant
A light year is defined as the distance light can travel at 3 × 10^8 m/s in one year (365 days). How far is one light year in kilometers? Enter your answer accurate to two decimal places in scientific notation