Physics A-Level
spectral class
What spectral class means in Physics A-Level, as defined for AQA.
Definitions of spectral class
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Reference: AQA
A labelling of the horizontal axis as OBAFGKM, where O is hottest on the left and M is coolest on the right, matching the temperature axis.
A class in which the Sun is placed, being class G, based on its surface temperature of approximately 5700 K.
Topics that use spectral class
- The Hertzsprung-Russell (HR) diagram (A-level only) (AQA A-Level)
Related terms
- absolute magnitude
- Giants and supergiants
- HR diagram
- Luminosity
- Main sequence
- Red giant branch
- Reversed temperature axis
- Surface temperature axis
Using spectral class in the exam
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