What this topic covers
Astrophysics (A-level only) has 3 subtopics:
- Telescopes (A-level only)
- Classification of stars (A-level only)
- Cosmology (A-level only)
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A Level AQA Physics · Topic 9 of 13
Astrophysics (A-level only) – A Level AQA Physics revision notes
Choose a subtopic. Astrophysics (A-level only) covers Telescopes (A-level only), Classification of stars (A-level only), and Cosmology (A-level only) in A Level AQA Physics. 23 lessons in 3 subtopics.
Revise Astrophysics (A-level only) for A Level AQA Physics, including Telescopes (A-level only) and Classification of stars (A-level only).
23
Lessons
3
Subtopics
Astrophysics (A-level only) lessons by subtopic
23 lessons, grouped by subtopic.
Telescopes (A-level only)
- Telescope Resolution and Collecting Power: Explore the angular resolution, Rayleigh criterion, and collecting power of large diameter telescopes, relating diameter to performance.
- Detectors: CCD vs. Eye: Compare and contrast the eye and CCD as detectors in telescopes, focusing on quantum efficiency, resolution, and ease of use.
- Ray Diagrams for Astronomical Telescopes: Learn how to draw and interpret ray diagrams for astronomical telescopes in normal adjustment.
- Angular Magnification of Telescopes: Understand and apply the concept of angular magnification, including its definition and calculation using focal lengths.
- Cassegrain Reflecting Telescopes: Explore the Cassegrain arrangement in reflecting telescopes, tracing ray diagrams and understanding the path of light.
- Reflectors vs. Refractors: Compare and contrast reflecting and refracting telescopes, qualitatively examining spherical and chromatic aberration.
- Radio vs. Optical Telescopes: Explore the structural and functional similarities and differences between radio and optical telescopes.
Classification of stars (A-level only)
- Apparent Magnitude and the Hipparcos Scale: An introduction to apparent magnitude, the Hipparcos scale, and how they relate to the brightness of stars.
- Stellar Spectral Classes: O, B, A: Explore the characteristics of O, B, and A type stars based on their spectra and temperature. Understand the key features that define these stellar classes.
- Stellar Spectral Classes: F, G: Learn about the properties of F and G type stars, including their spectral lines, temperature ranges, and notable examples within these classes.
- Stellar Spectral Classes: K, M: Investigate the characteristics of K and M type stars, focusing on their spectral features, relatively low temperatures, and their prevalence in the universe.
- Absolute Magnitude and Distance Modulus: Learn about the parsec and light year, and explore the relationship between absolute magnitude (M), apparent magnitude (m), and distance (d).
- Black-Body Radiation Laws: Stefan's and Wien's: Explore Stefan's law and Wien's displacement law, understanding how they relate to black-body radiation and temperature. Learn to estimate the temperature of stars using Wien's law and understand the key assumptions.
- Inverse Square and Stefan's Law: Stellar Properties: Apply the inverse square law and Stefan's law to analyze stars. Make the required assumptions and learn how to compare the power output, temperature, and size of stars using Stefan's Law.
- Hertzsprung-Russell Diagram Basics: An introduction to the Hertzsprung-Russell diagram, its axes, and the location of different types of stars.
Cosmology (A-level only)
- The Challenge of Detecting Exoplanets: An introduction to the difficulties involved in directly detecting exoplanets due to their small size and immense distance.
- Radial Velocity & Transit Methods: Learn about the two primary methods for exoplanet detection: variations in Doppler shift (radial velocity method) and the transit method.
- Discovering Quasars: Bright Giants of the Universe: Explore the initial discovery and properties of quasars as powerful radio sources and distant objects.
- Quasars: Supermassive Black Holes and Energy Output: Investigate the formation of quasars from supermassive black holes, their red shifts, and how to estimate their distance and power output.
- Hubble's Law and Redshift: Explore Hubble's Law and redshift as evidence for the expansion of the universe.
- The Expanding Universe and Age Estimation: Investigate the interpretation of Hubble's Law as evidence for an expanding universe and estimate its age.
- Big Bang Theory and Evidence: Examine the Big Bang theory, including evidence from cosmological microwave background radiation and the relative abundance of hydrogen and helium.
- Doppler Effect in Astronomy: Explore the Doppler effect and its applications in astronomy, including calculations for binary stars, galaxies, and quasars.
More in this course
Go back to the full A Level AQA Physics topic list, or practise this topic with past-paper questions.
Frequently asked questions
What is Astrophysics (A-level only)?
Astrophysics (A-level only) covers Telescopes (A-level only), Classification of stars (A-level only), and Cosmology (A-level only) in A Level AQA Physics. 23 lessons in 3 subtopics.
What is a light year?
A light year is the distance light travels in one year in a vacuum, about 9.46 × 10¹⁵ m, found from c = 3.0 × 10⁸ m s⁻¹ and about 3.156 × 10⁷ seconds in a year. The Absolute Magnitude and Distance Modulus notes cover this in full.
What is the Big Bang theory?
The Big Bang theory proposes that the universe began approximately 13.8 billion years ago from an extremely hot, dense state and has been expanding and cooling ever since. The Big Bang Theory and Evidence notes cover this in full.
What is Stefan's law?
Stefan's law states that the total power radiated per unit surface area of a black body is proportional to the fourth power of its absolute temperature: P/A = σT⁴, with σ = 5.67 × 10⁻⁸ W m⁻² K⁻⁴. The Black-Body Radiation Laws: Stefan's and Wien's notes cover this in full.
What is a quasar?
A quasar, or quasi-stellar radio source, is an extremely luminous, compact extragalactic object first identified as a strong radio source with a star-like optical appearance. The Discovering Quasars: Bright Giants of the Universe notes cover this in full.
What is a parsec?
A parsec is the distance at which the mean Earth–Sun separation, 1 AU, subtends an angle of exactly 1 arcsecond. The Absolute Magnitude and Distance Modulus notes cover this in full.
What does α mean in angular magnification?
In angular magnification, α is the angle subtended at the unaided eye by the object, and β is the angle subtended at the eye by the final image, so M = β/α. The Angular Magnification of Telescopes notes cover this in full.
What is the Rayleigh criterion?
The Rayleigh criterion states that two point sources are just resolvable when the central maximum of one diffraction pattern falls on the first minimum of the other. The Telescope Resolution and Collecting Power notes cover this in full.
What is a Cassegrain telescope?
A Cassegrain reflecting telescope uses a large parabolic concave primary mirror and a smaller convex secondary mirror. The Cassegrain Reflecting Telescopes notes cover this in full.