THE DOPPLER EFFECT
2 marks · EasyA galaxy is observed with its spectral lines shifted towards longer wavelengths.
(a)[1 mark]
What is this effect called?
(b)[1 mark]
What does this tell us about the motion of the galaxy relative to Earth?
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(a) Red-shift
(b) The galaxy is moving away from Earth.
Common mistakes: Naming the effect incorrectly; Saying the galaxy is moving closer
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Marking points
B1 (a) · 1 mark · Names the effect as red-shift.
B1 (b) · 1 mark · States the galaxy is moving away from Earth.
Worked solution
a) The effect is called red-shift.
b) This means the galaxy is moving away from Earth.