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Bright Objects
Table 1
Wavelength
Temperature
Wavelength
(nm)
Region of
Spectrum
Kelvin
Fahrenheit
Sirius A
293
Ultraviolet-
Infrared
9900
17360.33
Sun
500
Ultraviolet-
Infrared
5800
9980.33
Light Bulb
966
Visible-Infrared
3000
4940.33
Human Vision
Shortest wavelength: nm 383
Longest wavelength: nm 777
Questions
1)
Which two of the three objects in Table 1 have their peak intensity outside the visible
part of the spectrum?
Answer
: Sirius A and the Sun
2)
We can see all three objects clearly in the visible part of the spectrum, even though the peak intensity might lie outside that region. Why is this so?
Answer
: They release light at different times from peak to peak, so we can see more than just their peak.
3)
How is the wavelength of the most intense emission related to surface temperature?
Answer
: The peak point leans further toward ultraviolet wavelengths at increasing temperatures.
4)
At what wavelength does the Sun emit its most intense radiation? The Sun usually appears yellow to the human eye. What is the wavelength for yellow light? Are these the same or not? How is this related to the normal limits of human vision?
