Exam Focus — Red Shift and Big Bang

🎯 Exam Focus — Red Shift and Big Bang

Examined in Edexcel 1PH0/1 (Paper 1). Edexcel includes more quantitative red-shift and Hubble's Law work at Higher tier than most other boards — expect calculation questions using v = H₀d alongside qualitative "explain" questions. Context-based: real galaxy spectra and redshift measurements.

Most Common Question Types

• Explain what red shift is and what it tells us about the universe [3-4 marks]
• State two pieces of evidence for the Big Bang [2 marks]
• Explain what the CMBR is and why it is evidence for the Big Bang [3 marks]
• Describe what happens to wavelength when a galaxy moves away [2 marks]
• Explain why more distant galaxies have greater red shift [2 marks]

What Examiners Want to See

For "explain what red shift tells us" questions, a full-mark answer needs: wavelength increases as galaxy moves away → this is red shift → more distant galaxies have greater red shift → so they are moving away faster → the universe is expanding. For CMBR, examiners want to see: it comes from all directions, it was predicted before discovery, and it is the cooled remnant of the early hot universe.