____ has (have) wavelengths that are longer than visible light
a. Gamma-rays
b. Ultraviolet light
c. Infrared radiation
d. X-rays
e. a, b and d above
C
You might also like to view...
Two concentric spheres 0.2 m and 0.3-m in diameter, with the space between them evacuated, are to be used to store liquid air (133 K). If the surfaces of the spheres have been flashed with aluminum and the liquid air has a talent heat of vaporization of 209 kJ/kg, determine the number of kilograms of liquid air evaporated per hour.
GIVEN
• Two concentric spheres with the space between them evacuated and liquid air in the inner sphere
• Diameters ? D1 = 0.2 m ? D2 = 0.3 m
• Liquid air temperature (Ta) = 133 K
• Room temperature (T?) = 293 K
• Surfaces of the spheres have been flashed with aluminum
• Heat of vaporization of liquid air (hfg) = 209 kJ/kg = 209,000 J/kg
FIND
• The number of kilograms of liquid air evaporated per hour ( )m
ASSUMPTIONS
• Steady state
• Convective thermal resistance between the liquid air and interior sphere is negligible
• Thermal resistance of the sphere walls is negligible
• Natural convection on the exterior is negligible
• The room behaves as a blackbody enclosure
• The thickness of the sphere walls in negligible
SKETCH
PROPERTIES AND CONSTANTS
the Stephan-Boltzmann constant (?) = 5.67 × 10–8 W/(m2 K4)
the hemispherical emissivity of the spheres will be approximated by that for oxidized aluminum at 310 K: ? = ?1 ? 2 = 0.11
A standard candle is
A) a 7-cm-long wax candle. B) a light source of known luminosity. C) another name for a main-sequence star. D) another name for a barred-spiral galaxy.
The proper time interval between two events is measured from the frame of reference of an observer present at both events. Therefore, the proper time measurement of the decay of a neutron is measured by
A. an observer at the speed of light, relative to the neutron. B. an observer who is emitting light at all frequencies. C. an imaginary observer riding along with the neutron. D. an observer in the national lab at Los Alamos or any other certified nuclear lab.
The Sun's life time is 10 billion years. About how long is the lifetime of a star with a star has a mass of 0.1 MSun and a luminosity of 0.01 LSun?
A) 1 billion years B) 100 million years C) 100 billion years D) 10 million years