Photo AI
The origin of the Universe (a) Red giant and red shift are terms used in astronomy - Edexcel - GCSE Physics - Question 5 - 2017 - Paper 1
Question 5
The origin of the Universe (a) Red giant and red shift are terms used in astronomy. (i) Describe what is meant by red giant. (ii) Describe what is meant by red sh... show full transcript
Worked Solution & Example Answer:The origin of the Universe (a) Red giant and red shift are terms used in astronomy - Edexcel - GCSE Physics - Question 5 - 2017 - Paper 1
Step 1
Describe what is meant by red giant.
Answer
A red giant is a stage in the life of a star that occurs after it has exhausted the hydrogen in its core. At this point, the star expands and cools, having characteristics such as a larger size and a reddish hue. This phase signifies the transition from the main sequence stage to a later phase of stellar evolution.
Step 2
Describe what is meant by red shift.
Answer
Red shift refers to the phenomenon where light from distant celestial objects shifts towards the red end of the spectrum, indicating that these objects are moving away from the observer. This is a result of the Doppler effect and is used in astronomy to determine the speed and distance of galaxies, providing evidence for the expansion of the universe.
Step 3
Use the equation to calculate the recessional speed of the galaxy.
Answer
To find the recessional speed, we first need to calculate the change in wavelength:
Change in wavelength = Wavelength of distant galaxy - Wavelength of the line on Earth Change in wavelength = 478 nm - 434 nm = 44 nm
Now, we can apply the formula:
Substituting the values:
Calculating this gives: