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