This set of Solar Energy Multiple Choice Questions & Answers (MCQs) focuses on “Measurements of Solar Radiation – 1”.
1. What are the two basic ways to measure solar radiation?
a) Ground-based instrumentation and satellite measurement
b) Telephonic measurement and mobile tower measurement
c) Anemometer and voltmeter
d) Ammeter and voltmeter
View Answer
Explanation: Thee two basic ways to measure solar radiation are via ground-based instruments and satellite measurements. Anemometer is an instrument used to measure wind speed. Voltmeter is an instrument used to measure potential difference between two points conducting electric (DC) current. Ammeter is an instrument used to measure the electric (DC) current flowing across two points.
2. What is does an actinometer measure?
a) Wind speed
b) Intensity of radiation
c) Wind direction
d) Direction of radiation
View Answer
Explanation: Actinometer is used to measure the intensity of an incident radiation. Wind speed and wind direction are measured by anemometer and wind vane respectively.
3. Actinometer is primarily used to measure ______ and ______
a) infrared and ultraviolet
b) visible and infrared
c) visible and ultraviolet
d) infrared and UV-A
View Answer
Explanation: Actinometer is primarily used to measure visible and ultraviolet range. It does this by measuring the heating power of the radiation.
4. How does actinometer work?
a) By determining the number of electrons in a beam integrally
b) By determining the number of protons in a beam differentially
c) By determining the direction of photons
d) By determining the number of photons integrally
View Answer
Explanation: Actinometer works by determining the number of photons integrally or per unit time. It is commonly applied to devices used in UV and visible range.
5. As a system, actinometer is a _____ or _______
a) chemical system or physical device
b) chemical system or thermal device
c) thermal device or mechanical device
d) thermo-mechanical system or physical device
View Answer
Explanation: As a system, actinometer is a chemical system or physical device. Solutions Iron (III) oxalate is a commonly used example and is a chemical actinometer. Bolometers can be used as physical devices.
6. Which of the following categories does a pyranometer belong to?
a) Voltmeters
b) Actinometers
c) Hall sensors
d) Amplifiers
View Answer
Explanation: A pyranometer belongs to the category of actinometer because it is used for measuring solar irradiance. Voltmeters are used to measure potential difference between two electrically conducting points. Hall sensors are used to measure current via magnetic fields. Amplifiers are used to “amplify” currents or voltages.
7. Global and diffuse solar radiation can be measured by ________
a) thermal actinometer
b) heat pumps
c) thermoelectric pyranometers
d) oscilloscopes
View Answer
Explanation: Global and diffuse solar radiation can be measured by thermoelectric pyranometers. Heat pumps are used in thermal systems to pump heat from a cooler region to a hotter region. Oscilloscopes are used to observe sinusoidal outputs.
8. To perform irradiance measurement, which of the following is necessary?
a) Beam response varies with sine of the angle of incidence
b) Beam response varies linearly with angle of incidence
c) Beam response is constant with varying angle of incidence
d) Beam response varies with cosine of the angle of incidence
View Answer
Explanation: To perform irradiance measurement, it is necessary that the beam response varies with cosine of the angle of incidence. If the beam response is constant with varying angle of incidence then no measurement is performed.
9. Why should the beam response vary with cosine of the angle of incidence?
a) To account for perpendicular and parallel rays
b) Because cosine is the simplest mathematical function
c) To account for inclination of earth’s axis
d) Because of non-uniform dispersion of solar radiation
View Answer
Explanation: The beam response should vary with cosine of the angle of the incidence. This is to account for perpendicular and parallel rays. Angle of incidence is 0 degrees (i.e. full response) when the solar radiation hits the sensor normally and 90 degrees (i.e. zero response) for parallel rays from the sun when it is at the horizon.
10. Which of the following best describes the working of thermoelectric pyranometer?
a) Solar radiation → thermal e.m.f measured → thin black surface → rise in temperature until equilibrium
b) Solar radiation → thin black surface → rise in temperature until equilibrium → thermal e.m.f measured
c) Thin black surface → solar radiation → rise in temperature until equilibrium → thermal e.m.f measured
d) Solar radiation → rise in temperature until equilibrium → thin black surface → thermal e.m.f measured
View Answer
Explanation: A pyranometer consists of a thin-blackened surface on which the solar radiation falls. As the radiation hits the surface, the temperature rises until an equilibrium is attained. This rise in temperature sets a thermal e.m.f which is then measured.
11. Which of the following is generally used to measure direct solar radiation?
a) Pyranometer
b) Actinometer
c) Pyrheliometer
d) IC tester
View Answer
Explanation: Generally, a pyrheliometer is used to measure direct solar radiation. Actinometer are a class of devices/systems that measure intensity of radiation. IC tester is used to test ICs.
12. What technologies are used in pyranometers?
a) Silicon semiconductor technology and routing technology
b) Thermopile technology and doping
c) Doping and routing technology
d) Silicon semiconductor technology and thermopile technology
View Answer
Explanation: Thermopile technology and silicon semiconductor technology are used in pyranometers. Doping is a technique to increase the conductivity of intrinsic semiconductors. Routing is a technique used to navigate packets through an interconnected network of computers.
13. __________ is a physical device that can be correlated to the number of photons detected.
a) Photodiode
b) LEDs
c) CFLs
d) CFCs
View Answer
Explanation: Photodiode is a physical device that can be correlated to the number of photons detected. LEDs and CFLs are devices that emit light (radiation). CFCs are a type of gas that harm the ozone layer.
14. Light sensitivity is known as spectral response.
a) True
b) False
View Answer
Explanation: Light sensitivity is known as spectral response. It talks about how sensitive the photosensor is to optical radiation of various wavelengths. It depends on the type of pyranometer. It is an intensity vs wavelength plot.
15. Pyranometer has a non-directional response.
a) True
b) False
View Answer
Explanation: Pyranometer has a directional response. Since the beam response is required to vary with the cosine of angle of incidence, pyranometer has a directional or cosine response.
Sanfoundry Global Education & Learning Series – Solar Energy.
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