A-Level Physics OCR A H556

5.5.3: Cosmology

#5.5.3a

distances measured in astronomical unit (AU), light-year (ly) and parsec (pc)

#5.5.3b

stellar parallax; distances the parsec (pc)

#5.5.3c

the equation $p = \dfrac{1}{d}$ where p is the parallax in seconds of arc and d is the distance in parsec

#5.5.3d

the Cosmological principle; universe is homogeneous, isotropic and the laws of physics are universal

#5.5.3e

Doppler effect; Doppler shift of electromagnetic radiation

#5.5.3f

Doppler equation $\dfrac{Δλ}{λ} ≈ \dfrac{Δf}{f} ≈\dfrac{v}{c}$ for a source ofelectromagnetic radiation moving relative to an observer

#5.5.3g

Hubble’s law; $v ≈ H_0d$ for receding galaxies, where H₀ is the Hubble constant

#5.5.3h

model of an expanding universe supported by galactic red shift

#5.5.3i

Hubble constant H₀ in both kms^–1Mpc^–1 and s^–1 units

#5.5.3j

the Big Bang theory

#5.5.3k

experimental evidence for the Big Bang theory from microwave background radiation at a temperature of 2.7 K

#5.5.3l

the idea that the Big Bang gave rise to the expansion of space-time

#5.5.3m

estimation for the age of the universe; $t ≈ H_0^{-1}$

#5.5.3n

evolution of the universe after the Big Bang to the present

#5.5.3o

current ideas; universe is made up of dark energy, dark matter, and a small percentage of ordinary matter.

5.5.2

Electromagnetic radiation from stars

6.1.1

Capacitors