COSMIC MICROWAVE BACKGROUND (CMB) RADIATION

2 marks · Easy

Light from a distant galaxy has a wavelength of 550 nm, while the same spectral line measured from our Sun is at 500 nm. Calculate the speed at which the galaxy is moving away from Earth. (speed of light m/s)

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3.0 × 10⁴ km/s (±1000)

Also accept: 30,000 km/s; 3.0 × 10^4 km/s

Common mistakes: Leaving answer in m/s; Incorrect subtraction numerator

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Marking points

M1 · 1 mark · Uses the equation with correct values substituted.

A1 · 1 mark · Evaluates final answer correctly as 30,000 km/s (allow credible range due to rounding).

Worked solution