# Pulp & Paper Questions and Answers – Blackbody Radiations and Other Light Sources

This set of Pulp and Paper Questions and Answers for Entrance exams focuses on “Blackbody Radiations and Other Light Sources”.

1. A __________ is an object that absorbs all electromagnetic radiation that falls on it.
a) Grey body
b) Black body
c) Red body
d) White body

Explanation: A black body is an idealized physical body that absorbs all incident electromagnetic radiation. A white body is one with a rough surface which reflects all incident rays completely and uniformly in all directions.

2. The rate of radiation emitted from a blackbody is not a function of temperature only and is dependent of the type of material.
a) True
b) False

Explanation: Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. Matter with a temperature greater than absolute zero emits thermal radiation.

3. The energy of the emitted radiation at a given wavelength R (v) was derived by __________ is given as a function of frequency (v), the speed of light in a vacuum (c), temperature (T), and Boltzmann’s constant (k).
a) Einstein
b) Planck
c) Boltzmann
d) C. V. Raman

Explanation: The law describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium at a given temperature T. The law is named after Max Planck, who proposed it in 1900.

4. The relationships shown in this section strictly apply to only a single wavelength of light
a) True
b) False

Explanation: The relationships shown in this section strictly apply to only a single wavelength or a relatively narrow band of wavelengths of light and preferably measurements taken with the same light source and geometry.

5. The utilize of __________ gases allows the temperature at which a tungsten light operates to inc.. This gives a whiter distribution of light and inc. the efficiency of the light. __________ lights operate in the temperature range of 2800—3400 K.
a) Metal
b) Chalcogens
c) Halogens
d) Noble gases

Explanation: All of the halogens form acids when bonded with hydrogen. Most halogens are typically produced from minerals or salts. The central halogens, that is chlorine, bromine and iodine, are often utilized as disinfectants.

6. Light sources are often described by their __________ temperature, i.e., the spectral distribution of a blackbody radiator of a specified temperature that most closely matches the light source.
a) Colour
c) Frequency
d) Wave number

Explanation: The color temperature of a light source is the temperature of an ideal black-body radiator that gives out light of comparable hue to that of the light source. Color temperature is a characteristic of visible light that has imp. applications in lighting, photography, videography, publishing, and other fields.

7. Light could be produced by the excitation of molecules often by an electric charge, but also by the processes of fluorescence and combustion in addition to blackbody radiation. This mechanism produces different __________
a) Energy distribution
b) Molecular weight

Explanation: Distributed generation, also distributed energy, on-site generation (O.S.G.) or de-centralized energy is generated or stored by various small, grid-connected devices referred to as distributed energy resources (D.E.R.) or distributed energy resource systems.

8. Light is modified by filters to achieve certain purposes. The blue filter centred at 457 nm for paper brightness is well known __________ utilized to remove the I.R. energy from blackbody radiation sources.
a) Heat filters
d) UV filters

Explanation: H.V.A.C. stands for heating, ventilating/ventilation, and air conditioning is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality. The system design is a sub discipline of mechanical engineering, based on the principles of heat transfer, fluid mechanics, and thermodynamics.

9. __________ filters are utilized for purpose, especially with high—temperature blackbody radiation, where large amounts of U.V. light (which could cautilize eye and skin damage) are produced.
a) Heat
b) UV
c) Grey body
d) Dye

Explanation: It’s defined as a body with constant emissivity over all wavelengths and temperature Such an ideal body doesn’t exist in practice but the assumption is a good nearly for many objects utilized in engineering.

10. Dyes and pigments behave differently because they absorb light that is not part of the given colour. This is called _________
b) Subtractive mixing
c) Pigment mixing

Explanation: Subtractive color mixing is the one you get if you illuminate colored filters with white light from behind. The commonly utilized subtractive primary colors are cyan, magenta, and yellow, and if you overlap all 3 in effectively equal mixture, all the light is subtracted giving black.

Sanfoundry Global Education & Learning Series – Pulp and Paper.
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