 - 1. What is the calculated effective temperature of Earth in Kelvin, assuming an albedo of 0.309?
A) 255 K
B) 254.356 K
C) 245 K
D) 273 K
- 2. What is the effective temperature of the Earth expressed in degrees Celsius?
A) 18.8 °C
B) -18.8 °C
C) 1.36 °C
D) 0 °C
- 3. What is the solar surface temperature (TS) used in the Earth effective temperature calculation?
A) 6000 K
B) 5772 K
C) 5500 K
D) 5700 K
- 4. What value is used for the Earth's average emissivity (ε‾) in the primary calculation?
A) 0.95
B) Unity
C) 0.309
D) 0.5
- 5. If we treat the Earth as having no atmosphere, what body's albedo and emissivity are used as an estimate?
A) Mars
B) The Moon
C) The Sun
D) Venus
- 6. What is the estimated temperature of the Earth if we use the Moon's albedo and emissivity?
A) 1.36 °C
B) 245 K
C) 255 K
D) -18.8 °C
- 7. What is the estimated albedo of the Moon used in the calculation?
A) 0.3
B) 0.4
C) 0.309
D) 0.1054
- 8. What is the emissivity of the Moon used in the estimation provided in the text?
A) 0.1054
B) 0.309
C) 1.0
D) 0.95
- 9. Using an albedo of 0.4 and an insolation of 1400 W m−2, what is the effective temperature of Earth?
A) 273 K
B) 245 K
C) 254.356 K
D) 255 K
- 10. Using an albedo of 0.3 and a solar constant of 1372 W m−2, what is the effective temperature of Earth?
A) 255 K
B) 245 K
C) 273 K
D) 254.356 K
- 11. What typically raises the Earth's surface temperature above the effective temperature?
A) The Earth's emissivity
B) The Moon's albedo
C) Greenhouse effects
D) The solar constant
- 12. What is the stated range for the Earth's average albedo estimates?
A) 0.1–0.2
B) 0.3–0.4
C) 0.5–0.6
D) 0.8–0.9
- 13. What is the radius of the Sun (RS) provided for the calculation?
A) 1.496×1011 m
B) 6.957×1011 m
C) 5772 m
D) 6.957×108 m
- 14. What is the distance (D) between the Earth and the Sun used in the calculations?
A) 6.957×108 m
B) 1.496×1011 m
C) 5772 m
D) 1.496×108 m
- 15. What is the primary factor that determines the spectrum of black-body radiation?
A) Size
B) Temperature
C) Shape
D) Material
- 16. Who introduced the term 'black body' in 1860?
A) Max Planck
B) Stephen Hawking
C) Gustav Kirchhoff
D) Albert Einstein
- 17. What is another common term for black-body radiation?
A) Reflective glare
B) Thermal radiation
C) X-ray emission
D) Sonic radiation
- 18. What materials are considered good approximations to an ideal black material?
A) Polished silver and gold
B) Copper and aluminum
C) Glass and plastic
D) Graphite and lamp black
- 19. What happens to the peak frequency of black-body radiation as temperature increases?
A) It disappears
B) It shifts to higher frequencies
C) It shifts to lower frequencies
D) It remains constant
- 20. Why is a small hole in a large, uniformly heated cavity a good approximation of a black body?
A) The hole glows with ultraviolet light
B) The material of the hole is naturally black
C) The hole reflects all incoming light
D) Light entering the hole is likely to be absorbed after multiple reflections
- 21. What term is used to describe a surface whose spectral emissivity and absorptivity do not depend on wavelength?
A) Gray body
B) White body
C) Ideal black body
D) Lambertian radiator
- 22. According to Kirchhoff's Law in local thermodynamic equilibrium, what is true regarding emissivity and absorptivity?
A) Emissivity is always greater than absorptivity
B) Emissivity equals absorptivity
C) Emissivity is independent of the body's state
D) Absorptivity is always zero
- 23. What is Hawking radiation?
A) Radiation from the surface of the Earth
B) Hypothetical black-body radiation emitted by black holes
C) Radiation from room temperature objects
D) Visible light from the Sun
- 24. What is the primary reason why real objects are not perfect black bodies?
A) They are too small to emit radiation
B) They reflect or transmit some incident light
C) They are always too cold
D) They have no internal energy
- 25. At room temperature (296 K), in which part of the electromagnetic spectrum does a black body radiate mostly?
A) Infrared
B) Ultraviolet
C) Visible light
D) X-rays
- 26. What does a 'dazzling bluish-white' color indicate about a black body's emission?
A) It is at room temperature
B) It is at a very high temperature
C) It is cooling down
D) It is reflecting background light
- 27. What is a 'hohlraum' in the context of physics laboratory experiments?
A) A vacuum chamber
B) A cavity used to approximate a black body
C) A type of reflective mirror
D) A heat-resistant glass lens
- 28. What is the name of the problem where classical theory predicts infinite emission power?
A) Infrared catastrophe
B) Ultraviolet catastrophe
C) Thermal runaway
D) Black-body paradox
- 29. According to classical theory, what does the equipartition theorem imply about the energy in each mode?
A) No energy in any mode
B) Equal amount of energy in each mode
C) Energy proportional to frequency
D) Energy inversely proportional to frequency
- 30. Who solved the black-body radiation problem in 1901?
A) Josef Stefan
B) Ludwig Boltzmann
C) Albert Einstein
D) Max Planck
- 31. What term refers to the quantization of electromagnetic radiation proposed by Einstein?
A) Neutrinos
B) Electrons
C) Photons
D) Quarks
- 32. Which law determines the wavelength at which radiation is strongest?
A) Wien's displacement law
B) Stefan–Boltzmann law
C) Planck's law
D) Kirchhoff's law
- 33. What is the relationship between irradiance Bν(T,E) and photon flux density bν(T,E)?
A) Bν(T,E) = bν(T,E) - E
B) Bν(T,E) = E / bν(T,E)
C) Bν(T,E) = E + bν(T,E)
D) Bν(T,E) = E * bν(T,E)
- 34. In the formula for Bω(T), what symbol is used instead of h?
A) ħ
B) π
C) λ
D) μ
- 35. According to the Stefan–Boltzmann law, the power emitted per unit area of a black body is proportional to what power of its absolute temperature?
A) First power
B) Cube
C) Fourth power
D) Square
- 36. What is the approximate net radiative heat loss for an adult human in typical room conditions?
A) 500 W
B) 10 W
C) 100 W
D) 2000 W
- 37. In the context of human thermal loss, which mechanism is considered negligible?
A) Convection
B) Conduction
C) Radiation
D) Evaporation
- 38. What is the approximate numerical solution for x in the unitless Planck's law peak frequency equation?
A) 2.82
B) 1.00
C) 5.67
D) 9.50
- 39. Which of the following is an example of internal energy generation in a planet?
A) Solar wind
B) Reflection of light
C) Radioactive decay
D) Stellar luminosity
- 40. What effect causes a fraction of light to be reflected by a planet?
A) Adiabatic expansion
B) Albedo effect
C) Greenhouse effect
D) Tidal heating
- 41. What fraction of the Sun's light does a planet absorb if its albedo is α?
A) 1+α
B) α
C) 1-α
D) α/2
- 42. What shape is used to calculate the cross-sectional area of a planet absorbing solar radiation?
A) Triangular area
B) Circular area
C) Elliptical area
D) Square area
- 43. Which of the following is considered a source of internal planetary heat?
A) Tidal heating
B) Interplanetary dust
C) Solar flares
D) Stellar gravitational pull
- 44. What state was most matter in prior to the decoupling of matter and radiation?
A) Condensed gas
B) Ionized plasma
C) Neutron star matter
D) Solid crystal
- 45. Who introduced the notion of a black body in 'Opticks'?
A) Isaac Newton
B) Pierre Prevost
C) Augustin-Jean Fresnel
D) Balfour Stewart
- 46. What substance did Balfour Stewart use as his reference for absorbing and radiating power?
A) Reflective silver
B) Lamp-black
C) Glass plates
D) Polished tungsten
- 47. What is lamp-black made from?
A) Synthetic polymer dust
B) Refined mineral oil
C) Crushed carbon crystals
D) Soot from burning organic materials
- 48. Which principle did Balfour Stewart's research on rays obey?
A) The law of universal gravitation
B) Stokes-Helmholtz reciprocity principle
C) The uncertainty principle
D) Newton's Law of Cooling
- 49. In what year did Gustav Robert Kirchhoff report the coincidence of the wavelengths of spectrally resolved lines of absorption and emission?
A) 1862
B) 1900
C) 1859
D) 1860
- 50. Did Kirchhoff's 1859 report on the general principle of radiation mention black bodies?
A) No
B) Yes, he provided a full definition of black bodies
C) Yes, they were the primary focus
D) Yes, but only in the appendix
- 51. According to Helge Kragh, what field owes its origin to the study of blackbody radiation?
A) Quantum theory
B) General relativity
C) Electromagnetism
D) Classical mechanics
- 52. In the simplified temperature shift formula for a moving black body, what does v > 0 indicate?
A) Approaching source
B) Stationary source
C) Collapsing source
D) Receding source
- 53. In the simplified temperature shift formula for a moving black body, what does v < 0 indicate?
A) Approaching source
B) Accelerating source
C) Receding source
D) Stationary source
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