Extra Problems - Light and Atoms
You will find the following numbers useful.
The speed of light is 3x105 km-sec-1.
1 AU is 1.5x108 km.
One year = about 3x107 seconds.
- How long does it take light to travel from the Sun to Neptune? (Neptune is roughly 30 AU from the Sun).
- A star has surface temperature of 18,000 K. Use Wien's Law to find at what wavelength it radiates most strongly.
- A dim star radiates most strongly at 1500 nm. Use Wien's Law to find its surface temerpature.
- A galaxy shows a spectrum line at 800 nm which in the laboratory is at 600 nm. What is the galaxy's speed?