P 6. Using Radiation to investigate stars Flashcards
How is an emission spectra formed?
(4 things)
- Element within gas being heated
- Causes electron to transition and go back down
- Emitting certain wavelengths (coloured lines)
- Creating an emission spectra
How is an absorption spectra formed?
(4 things)
- When emitted radiation passes through a star’s atmosphere
- A line absorption spectrum is produced
- Where atoms absorb certain wavelengths
- Of the electromagnetic spectrum
Explain emission of radiation by an atom?
(6 things)
- Electron in an excited state
- Atom drops back down from 1 energy to another
- Emitting left over energy as a photon
- Change in energy between states = energy of photon
- △E = hc/λ
- Produces lines on spectra at each transition wavelength
Explain absorption of radiation by an atom?
(6 things)
- Electron from a lower state
- Goes up to a higher energy state
- From being heated
- Electron can only absorb energy = a transition in energy states (△E)
- Electron absorbs a photon where △E = hc/λ
- Produces dark lines in continuous spectra of radiation incident on the atom
Tell me about the sun’s spectra
(3 things)
- A continuous spectrum
- Crossed by many dark lines
- ∴ complex combination of a continuous emission spectrum and a line absorption spectrum
Explain the dark absorption lines in the sun’s spectra?
(2 things)
- Due to the outer atmosphere of the sun
- Absorbing only certain wavelengths of radiation
Explain why black lines are present
(6 things)
- Black lines appearing as a packet of quantised energy
- Emitted as photons in all directions
- from the cloud of gas absorbing energy packets
- from a certain source
- in order to move to higher energy states.
- Tries to be stable from emitting packets of quantised energy
How can black lines from a spectra help to find info of the composition of a star?
(3 things, can’t believe u didn’t know what composition is)
- Different elements give off different wavelengths
- Which would show based on the lines position in spectra
- Determines what elements present in the sun
Define the terms “black-body”?
(3 things)
- An object that doesn’t reflect any light incident upon it
- Appears black
- Absorbs 100% of the radiation
Explain the energy distribution in the spectrum of a Black body?
(It’s the graph, 6 steps)
What u can conclude within “that graph”?:
1. Position of peak of curve depends on temperature of the body
2. As temp. increases, the peak wavelength decreases
3. Overall intensity increases as temperature increases
4. At low temperatures, most radiation is IR
5. At higher temperatures, shift towards visible (glows red hot)
6. Higher temperature black body’s have a more defined peak
How do u find the extremes of the visible light spectrum & colour?
By the heat that could be stated on the graph
State Wien’s law?
(2 things)
- The peak wavelength emitted by a hot object
- is inversely proportional to its absolute temperature
What’s the formula for Wien’s law?
λmax = W/T
Define λmax
(Wien’s law)
Peak wavelength (metres)
Define W
(Wien’s law)
Wien’s constant (2.9x10-3 metre-kelvin)
Define T
(Wien’s law)
Absolute temperature (°C +273.15 still big difference)
How do u sketch the shape of the curve for that Wien typa graph?
It’s like a rollercoaster
(Maybe I need a new place to make flashcards, I literally need pictures)
What’s the formula for Stefan’s law?
P = σAT4
Define Stefan’s law?
(P/A = σT4 -> P/A ∝ T4)
4 things
- The luminosity/power per unit area
- , of a black body,
- is directly proportional to the 4th power
- of it’s absolute temperature
Define P
(Stefan’s law)
Power/luminosity (W aka watts)
Define σ
(Stefan’s law)
Stefan constant (5.67 x 10-8 Wm<-2</sup>K-4
Define A
(Stefan’s law)
Area (m2 aka square meters)
Define T
(Stefan’s law)
Temperature (K aka kelvin)
Formula for Intensity of radiation?
Not in data booklet
Wm-2 = W/m2
Wm-2 = W/m2 in word form
Intensity = Power/Surface area
What about finding intensity in Wm-2 = W/m2?
Only intensity at it’s surface
The formula to gain intensity from a certain distance?
not given in data booklet
I1/I2 = r22/r12
Gain intensity from a certain distance explanation???
(lil check up tbh)
(major check up)
I1/I2 = r22/r12
Explanation:
I is just the intensity’s so u can just re-arrange for the intensity’s a certain one from their surface
r is also literally just the radius, so u may have to do some crazy ass re-arranging to gain radius or it tells u and u need to convert it to m. In addition remember to x based on how much further away the planet it.
Don’t forget to square, considering this not in data booklet
Use ur observations please :)
What is multi-wave astronomy?
- Making observations outside visible spectrum to investigate stars
Key features of multi-wave astronomy?
…. not just visible, all e-m spectrum
How do they even do multi-wave astronomy?
Use of variety of telescopes, outside atmosphere and inside
X-rays and gamma in multi-wave astronomy?
(2 things)
- Observes high energy phenomena
- ie. blacks holes & supernovas
UV in multi-wave astronomy?
Observes hot stars
Visible light in multi-wave astronomy?
Observes warmer stars and planets
IR in multi-wave astronomy?
Observes cool stars and core of our galaxy
Micro & radio waves in multi-wave astronomy?
Observes cold molecular clouds and radiation left over from the Big Bang
Ye maybe i’m fucked for this part, might even be everything at this point too :(
Ready to complete…. at what cost?
Absolute life saver, now I didn’t have to go yam just like maths
Hope for the best, BUT AT LEAST U HAVE NOTES READY TO BE COMPLETED LATER!!!
Everything, damn i woulda been cooked
Preciate it
Damn maths was bad then?
Also ig ima just have to clean this up
It definitely was
Yes yes
