Investigating Stars Flashcards
How is an absorption spectra produced
When photons of visible light pass through a cold gas, the photons with the same energy as the energy level as the electrons get absorbed and results in the electron jumping up an energy level, this is shown by the black lines.
How is an emission spectra produced
When a gas is heated, the electrons jump down energy level and release a photon of certain wavelength which is shown on the emission spectra.
Bohrs theory of emission spectra of hydrogen
Energy of a photon is proportional to the frequency of a photon wave
Why are black lines present on a suns emission spectrum and how information about the composition can be obtained from these lines
Due to nuclear fusion from the core of the sun it’ll emit a continuous spectrum. As the light travels through the suns atmosphere the gases present will absorb certain wavelengths of light, these wavelengths will be absent on a absoprtion spectrum. By matching the absorption spectrum with a known spectra on earth , the gases present can be identified
What is the range of a continuous spectrum
750nm Red-400nm Violet
How is a continuous spectrum produced
Continuous spectra arise from dense gases or solid objects which radiate heat. They emit radiation over a broad range of wavelengths, thus the spectra appear smooth and continuous.
What is a black body
A black body is an idealized object which absorbs all radiation incident on it. And emits the maximum radiation at each wavelength of the continuous spectrum.
What is considered to be a perfect black body
Stars
Wiens law
The peak wavelength emitted by a hot object is inversely proportional to its absolute temperature
Weins constant
2.90x10^-3
Equation for absolute temperature(K)
temp+273.15
Stefans law
The luminosity / power per unit area of a black body is directly proportional to the 4th power of its absolute temperature
Stefans constant
5.67x10^-8
Equation for intensity
Luminosty/power(W)/Surface Area (m^2)
I=P/4pir^2
Inverse Square law
I proportional to 1/r^2
