Cosmology

Summary and Exam Tips for Cosmology

Cosmology is a subtopic of Astrophysics, which falls under the subject Physics in the Edexcel IGCSE curriculum. The Big Bang Theory suggests that around 14 billion years ago, the Universe originated from a small, extremely hot, and dense region. This led to a massive explosion, known as the Big Bang, causing the Universe to expand from a single point. This expansion is evidenced by galaxies moving away from each other, with those further away moving faster. The Cosmic Microwave Background (CMB) radiation and galactic red-shift are key pieces of evidence supporting this theory. CMB radiation, discovered in 1964, is a remnant from the early Universe, uniformly spread with a temperature of 2.73 K. The Doppler Effect explains the redshift observed in light from distant galaxies, indicating they are moving away, thus supporting the Universe's expansion. This redshift shows that the further a galaxy is, the faster it recedes, aligning with the Big Bang Theory. The Doppler shift can be calculated using the equation $\Delta \lambda = \lambda - \lambda_0$, where $\lambda$ is the observed wavelength, and $\lambda_0$ is the reference wavelength.

Exam Tips

• Use precise scientific terms: Avoid vague words like "it" or "they" without clear context.
• Understand the question: Differentiate between 'what' and 'why' questions to provide accurate answers.
• Mark allocation: Let the number of marks guide the depth of your answer.
• Explain concepts clearly: When discussing effects like the Doppler Effect, ensure you explain how it relates to the topic.
• Practice calculations: Be comfortable with equations like the Doppler shift to calculate galaxy velocities.