Sustainable Energy Technology Nptel Week 5 Answers
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Sustainable Energy Technology Nptel Week 5 Answers (July-Dec 2025)
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Question 1. The global horizontal irradiance is the sum of direct normal irradiance and diffuse horizontal irradiance.
a) True
b) False
Question 2. Black plate in flat plate collector emits shortwave radiation and absorb longwave radiation.
a) True
b) False
Question 3. During an equinox, the length of day and night are approximately equal all over the world.
a) True
b) False
Question 4. Solar thermal system uses sunlight to generate electricity directly without converting it into heat first.
a) True
b) False
Question 5. The efficiency of a concentrated solar thermal power system increases linearly with the rising temperature of the hot fluid.
a) True
b) False
Question 6. Evacuated tubes solar collector is more efficient than flat plate collector in cold and cloudy climate.
a) True
b) False
Question 7. The daily solar insolation received during the summer months is different for all latitudes of the Northern Hemisphere.
a) True
b) False
Question 8. Hour angle is the measure of location of the sun in sky.
a) True
b) False
Question 9. Which of the following is not a commonly used type of solar thermal collector?
a) Flat plate collector
b) Parabolic dish collector
c) Evacuated tube collector
d) Photovoltaic panel
Question 10. A 8 m² flat plate collector has heat transfer resistance of 0.4 K/Watt. Its reflectivity is 0.4. At incident solar radiation of 420 W/m², what is its stagnation temperature? Use the linear relationship discussed in class to evaluate. Choose the closest answer.
a) 537 K
b) 706 K
c) 806 K
d) 510 K
These are Sustainable Energy Technology Nptel Week 5 Answers
Question 11. By how many times does the daily available solar energy per unit area of ground surface available at 12° N latitude exceed that available at 60° N latitude in the month of December (Use plots from lecture slide for your answer, choose the closest answer).
a) 2 times
b) 4 times
c) 8 times
d) 16 times
Question 12. The approximate value of solar constant is:
a) 1367 W/m²
b) 1000 W/m²
c) 1361 kW/m²
d) 500 W/m²
Question 13. Calculate the hour angle for the beam of radiation from the sun at a spot with co-ordinates (56° N, 4° W) at 9 am on day 30 of the year, assume that the surface is oriented 22° east of south and by 42° to the horizontal. The time zone meridian is 0°. Choose the answer closest to your calculated value.
a) 50°
b) -49°
c) 49°
d) 35°
Question 14. The angle between solar radiation and ground on the earth is called
a) Hour angle
b) Angle of incidence
c) Azimuth angle
d) Zenith angle
Question 15. Which among these absorb and re-emits longwave infrared radiation in flat plate solar collector?
a) Black flooded plate
b) Insolation
c) Absorber plate
d) Glass cover
Question 16. What is the solar declination angle – in degrees – on December 21 is: ____________ degrees
These are Sustainable Energy Technology Nptel Week 5 Answers
