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25. Astronomy and cosmology

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3 topics · 11 learning objectives

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  1. 25.1 Standard candles

    1. 25.1.1The term luminosity as the total power of radiation emitted by a star

      • understand the term luminosity as the total power of radiation emitted by a star

    2. 25.1.2The inverse square law for radiant flux intensity F

      • recall and use the inverse square law for radiant flux intensity F in terms of the luminosity L of the source F = L / (4πd 2)

    3. 25.1.3An object of known luminosity is called a standard candle

      • understand that an object of known luminosity is called a standard candle

    4. 25.1.4The use of standard candles to determine distances to galaxies

      • understand the use of standard candles to determine distances to galaxies

  2. 25.2 Stellar radii

    1. • recall and use Wien’s displacement law λmax ∝ 1 / T to estimate the peak surface temperature of a star

    2. • use the Stefan–Boltzmann law L = 4 πσr 2 T 4

    3. • use Wien’s displacement law and the Stefan–Boltzmann law to estimate the radius of a star

  3. 25.3 Hubble’s law and the Big Bang theory

    1. • understand that the lines in the emission and absorption spectra from distant objects show an increase in wavelength from their known values

    2. • use ∆λ / λ ≈ ∆f / f ≈ v / c for the redshift of electromagnetic radiation from a source moving relative to an observer

    3. • explain why redshift leads to the idea that the universe is expanding

    4. • recall and use Hubble’s law v ≈ H0d and explain how this leads to the Big Bang theory (candidates will only be required to use SI units)