Summary
Summary Astrophysics - OPTION MODULE
- Course
- Institution
Physics A Level, Astrophysics option module notes - 23 page document.
[Show more]
Seller
Follow
marlowetaylor
Reviews received
Content preview
AQA A LEVEL PHYSICSASTROPHYSICS SECTION
Marlowe Taylor
,Contents
Telescopes (9.1) .............................................................................................................................. 2
Astronomical telescope consisting of two converging lenses (9.1.1) ............................................... 2
Reflecting telescopes (9.1.2)......................................................................................................... 3
Single dish radio telescopes (9.1.3) ............................................................................................... 5
Advantages of larger diameter telescopes (9.1.4) ........................................................................... 7
Classification of stars (9.2) ............................................................................................................. 9
Classification by luminosity (9.2.1)................................................................................................ 9
Absolute magnitude, M (9.2.2) ...................................................................................................... 9
Classification by temperature, black-body radiation (9.2.3) .......................................................... 10
Principles of the use of stellar spectral classes (9.2.4) ................................................................. 11
The Hertzsprung-Russel (HR) diagram (9.2.5)............................................................................... 12
Supernovae, neutron stars and black holes (9.2.6) ....................................................................... 14
Cosmology (9.3) ............................................................................................................................ 16
Doppler effect (9.3.1).................................................................................................................. 16
Hubble’s law (9.3.2) .................................................................................................................... 18
Quasars (9.3.3)........................................................................................................................... 21
Detection of exoplanets (9.3.4) ................................................................................................... 22
, Telescopes (9.1)
- Converging lens – rays parallel to the optic axis are focussed at the principal focus
- Principal focus = the point on the principal axis where parallel light rays meet
- Focal length = distance along the optic axis between the centre of the lens and the principal
focus
1
- Power of a lens = unit = dioptre (D)
focal length
1 1 1 v
- Lens formula (for a converging lens): u + v = f
leads to magnification, M = u
o u = object distance, measured object to lens centre (always positive)
o v = image distance, measured lens centre to image (positive or negative)
o f = focal length of lens (always +ve)
For converging lenses:
Formation of a real image: Formation of a virtual image:
Object more than 1 focal length away from lens Object less than 1 focal length away from lens
u ≥ f image is inverted u ≤ f image is upright
Astronomical telescope consisting of two converging lenses (9.1.1)
- Refracting telescopes use two lenses in the normal adjustment
o Objective lens closer to the object, larger diameter, larger focal length
o Eyepiece lens closer to the eye, smaller diameter, smaller focal length
.
Rays don’t meet so a virtual image is
formed
.
Angular magnification occurs
.
image formed by objective lens lies at
focal point of eyepiece lens. Focal point
of eyepiece lens coincides with focal
point of objective lens
- Angular magnification in normal adjustment
o Light entering the objective enters from different
points on the object being viewed, but for a distant
object like a planet the angle between light from the
top of the object and the light from the middle of the
object is small
o Telescopes make an object appear to be closer than it
actually is – the angle changes while the actual height
of the object remains constant
angular size of image seen through the telescope focal length of objective
o angular magnification = angular size of image seen by unaided eye
= focal length of eyepiece
<
𝑎𝑛𝑔𝑙𝑒 𝑠𝑢𝑏𝑡𝑒𝑛𝑑𝑒𝑑 𝑏𝑦 𝑖𝑚𝑎𝑔𝑒 𝑎𝑡 𝑒𝑦𝑒 𝑓𝑜𝑏𝑗𝑒𝑐𝑡𝑖𝑣𝑒
- 𝑀 = 𝑎𝑛𝑔𝑙𝑒 𝑠𝑢𝑏𝑡𝑒𝑛𝑑𝑒𝑑 𝑏𝑦 𝑜𝑏𝑗𝑒𝑐𝑡 𝑎𝑡 𝑢𝑛𝑎𝑖𝑑𝑒𝑑 𝑒𝑦𝑒 = 𝑓𝑒𝑦𝑒𝑝𝑖𝑒𝑐𝑒
Length of telescope = 𝑓𝑜 + 𝑓𝑒
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller marlowetaylor. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $4.10. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
72349 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now