Photometrics Quiz (20 pts)

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Question 1: The PPFD unit µmol/m²/sec, corresponds to how many photons/m²/sec?

a) 6.023x10^16 b) 6.023x10^17 c) 1X10^16 d) 1X10^17

Question 2: The irradiance of 1 watt/m² contains more PPFD for which of the following coloured lights?

a) Red b) Yellow c) Blue d) The same for all colours

Question 3: What is the difference between Correlated Colour Temperature (CCT) and Colour temperature (CT)?

a) They are basically the same b) CCT is larger than CT. c) CCT is for a non-black body and CT is for a black body. d) CT is for a non-black body and CCT is for a black body.

Question 4: Which colour temperature is more suited for an office?

a) 3300 K b) 4000 K c) 4300 K d) 5300 K

Question 5: The relation between Lux to Candela is similar to which of the following radiometric relations?

a) Watt/m² to Watt b) Watt/sr/m² to Watt/sr c) Watt/m² to Watt/sr d) Watt to Watt/sr/m²

Question 6: What does the S/P ratio of a light source mean?

a) The ratio of the light intensities measured by sagittal and peripheral methods. b) The ratio of the light intensities measured by scotopic and photopic methods. c) The ratio of light intensities measured by scotopic and peripheral methods. d) The ratio of light intensities measured by sagittal and photopic methods.

Question 7: The lamps with high S/P have which of the following qualities?

a) Reduce one's ability to see both low light and well-lit conditions. b) Are well suited for low light conditions. c) Are well suited for well-lit conditions. d) Improve one’s ability to see both low light and well-lit conditions.

Question 8: What is the spectral range corresponding to far-red radiation?

a) 700-800 nm b) 700-900 nm c) 800-900 nm d) 1-5 µm

Question 9: What could be the CRI index of a low pressure sodium lamp, which is a monochromatic source?

a) 42 b) 51 c) Meaningless d) 89

Question 10: What are the corresponding wavelength ranges to UVA, UVB and UVC radiation?

a) 320-400nm, 250-320nm and 200-250nm b) 300-400nm, 250-300nm and 200-250nm c) 350-400nm, 290-350nm and 200-290 nm d) 320-400nm, 290-320 nm and 200-290 nm

Question 11: What is the wavelength range of visible light?

a) 390-680nm b) 300-1000nm c) 400-700nm d) 300-800nm

Question 12: A blue photon has _______ energy as compared to a red photon.

a) Less b) Zero c) More d) The same

Question 13: Which statement is most accurate about the difference between a photometer and a spectrometer?

a) A photometer measures light energy but a spectrometer measures the spectrum of light. b) A photometer measures the number of photons but a spectrometer measures the total energy. c) A photometer measures number of photons but a spectrometer measures wavelength of light. d) A photometer has a counter but a spectrometer does not have one.

Question 14: The Sun’s radiation is effectively a _______ black body radiation.

a) 300 K b) 5800 K c) 21 K d) 10,000 K

Question 15: The refractive index of a medium is the ratio of

a) The speed of light in that medium to the speed of light in vacuum. b) The speed of light to the speed of sound. c) The speed of light in vacuum to the speed of light in that medium. d) The density of a medium to the density of air.

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Question 16: If one Watt of 555 nm green light is equivalent to 683 lumens, what is the most likely lumen value for a 730 nm light?

a) 2.7 lumens b) 683 lumens c) 519 lumens d) 0 lumens

Question 17: What is the difference between absolute temperature and colour temperature?

a) Colour temperature is the absolute temperature of a coloured object at a particular temperature. b) They are basically the same. c) The colour temperature of an object is the temperature at which a black body emits radiation of the same colour as the object. d) Colour temperature is the product of absolute temperature and the absorption coefficient for a particular colour.

Question 18: Which statement about colour temperature is correct?

a) Warmer temperatures correspond to cooler colours. b) Colour temperature increases with increasing wavelength of light. c) Blue colour has low colour temperature. d) Red colour has typically a 5,000 K colour temperature.

Question 19: In the US, the light bulb packaging has the requirement to specify the output of the lamp in lumens. If the output of a 60 Watt incandescent lamp is marked as 900 lumens, which of the following compact fluorescent lamps is likely to have the same output in lumens?

a) 15 Watt b) 60 Watt c) 100 Watt d) 50 Watt

Question 20: What is the difference between the photometric units of candela and lumen?

a) Candela is a measure of luminous flux but lumen is a measure of luminance b) Candela is a measure of luminous intensity but lumen measures luminous power c) Candela is a measure of illuminance but lumen measures luminance d) Candela is a measure of illuminance but lumen measures luminous flux

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