Black-body radiation Quiz
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5 questions, one answer each
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1. What is the peak wavelength of a black body at 4000 K?
- A. 7.2 × 10⁻⁷ m
- B. 1.4 × 10⁶ m
- C. 11.6 m
- D. 7.2 × 10⁻¹⁰ m
2. The surface temperature of a star of fixed radius is tripled. By what factor does its luminosity increase?
- A. 3
- B. 9
- C. 27
- D. 81
3. Which change occurs when a black body is heated from 3000 K to 6000 K?
- A. The peak wavelength increases
- B. The peak wavelength is unchanged
- C. The peak wavelength decreases and the intensity increases at all wavelengths
- D. The peak wavelength decreases and the intensity falls at long wavelengths
4. Which expression gives the luminosity of a spherical star of radius r and temperature T?
- A. σrT⁴
- B. 4πr²σT⁴
- C. 4πr²σT²
- D. σT⁴/4πr²
5. Star X has twice the radius and half the surface temperature of star Y. What is L_X/L_Y?
- A. 1/4
- B. 1/2
- C. 1/8
- D. 2