Luminosity and intensity of stars Quiz
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5 questions, one answer each
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1. What is the SI unit of intensity?
- A. W
- B. W m⁻²
- C. W m⁻¹
- D. J m⁻²
2. A star's intensity at the Earth is 8.0 × 10⁻⁹ W m⁻². What is its intensity from twice the distance?
- A. 4.0 × 10⁻⁹ W m⁻²
- B. 1.6 × 10⁻⁸ W m⁻²
- C. 2.0 × 10⁻⁹ W m⁻²
- D. 6.4 × 10⁻⁸ W m⁻²
3. A star of luminosity 4.0 × 10²⁶ W is at 1.0 × 10¹⁸ m. What intensity does it produce?
- A. 3.2 × 10⁻¹¹ W m⁻²
- B. 4.0 × 10⁻⁸ W m⁻²
- C. 1.3 × 10⁻¹¹ W m⁻²
- D. 3.2 × 10⁻⁷ W m⁻²
4. Which quantity does NOT change as you move away from a star?
- A. Intensity
- B. Luminosity
- C. Power per unit area
- D. Apparent brightness
5. Star A has the same intensity at the Earth as star B, but twice the distance. What is L_A/L_B?
- A. 2
- B. 1/2
- C. 4
- D. 1/4