Cambridge IGCSE Physics

6.2.3The Universe

The Universe in Cambridge IGCSE Physics: what the syllabus expects you to know, the learning objectives and how to practise.

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Learning objectives

What the syllabus expects you to be able to do.

6.2.3.1Know that the Milky Way is one of billions of galaxies and is about 100 000 light-years across.
6.2.3.2Describe redshift as an increase in the observed wavelength of radiation from receding stars and galaxies.
6.2.3.3Know that light from distant galaxies is redshifted compared with light emitted on the Earth.
6.2.3.4Know that redshift from distant galaxies shows the Universe is expanding and supports the Big Bang theory.
6.2.3.5Supplement: know that cosmic microwave background radiation (CMBR) of a particular frequency is observed in every direction.
6.2.3.6Supplement: explain that the CMBR was produced shortly after the Universe formed and has been stretched into the microwave region by expansion.
6.2.3.7Supplement: know that a galaxy's speed away from the Earth can be found from the redshift of its starlight.
6.2.3.8Supplement: know that the distance to a far galaxy can be found from the brightness of a supernova in it.
6.2.3.9Supplement: define the Hubble constant H0 = v/d and use the equation.
6.2.3.10Supplement: know that the current estimate of H0 is 2.2 × 10⁻¹⁸ per second.
6.2.3.11Supplement: know that d/v = 1/H0 estimates the age of the Universe and supports the idea that all matter began at a single point.

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