6.2.1 The Sun as a Star
What is the Sun?
The Sun is a star of medium size, composed mainly of hydrogen and helium.
Where the Sun’s Energy Appears
- The Sun radiates most of its energy in the infrared, visible, and ultraviolet regions of the electromagnetic spectrum.
Key Terms (Quick Reminders)
| Term | Meaning |
|---|---|
| Star | Self-luminous sphere of hot gas powered by nuclear processes. |
| Hydrogen / Helium | Main elements in the Sun’s composition. |
| Infrared (IR) | EM radiation beyond red; carries heat. |
| Visible light | EM band seen by the human eye. |
| Ultraviolet (UV) | EM band beyond violet; higher energy than visible. |
| Electromagnetic spectrum | Continuous range of EM waves from radio to gamma. |
Exam Pointers
- Identify the Sun as a medium-sized star made mostly of hydrogen and helium.
- State that most emission is in the IR, visible, and UV bands.
- Use correct terminology for the electromagnetic spectrum regions.
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