Energy Systems – Bit Question Bank

1. The nuclear reaction responsible for solar radiation is ----------------------------------2. Sun’s blackbody temperature is -------------------------------------------3. Average temperature of earth is ----------------------------------------4. Ozone layer is in the ---------------------------------------- of earth’s atmosphere.5. Value of solar constant is ---------------------------------------6. Solar radiation received on earth’s surface is called -------------------------------------7. Wave length of ultra violet rays is -------------------------------------------8. Wave length of infrared rays is ------------------------------------------9. ----------------------------------- per cent of solar radiation is in visible light frequency.10. Vernal equinox occurs on -----------------------------------------11. Autumnal equinox occurs on --------------------------------------------12. Summer solstice occurs on ----------------------------------------13. Winter solstice occurs on ----------------------------------14. Diameter of earth is --------------------------------------------15. Diameter of sun is ------------------------------------------------16. Mean distance between Sun and earth is -------------------------------------------17. The plane of earth’s orbit is called -----------------------------------18. Earth’s polar axis is inclined to its orbital plane by ----------------- degrees.19. Length of day and night are equal on ------------------------------------------20. Longest night during the year occurs on ----------------------------------------21. Maximum solar radiation per day in India is --------------------------------------22. ---------------------------------------------------- is good material for making Fresnel lenses.23. Thermal collectors with line focus use -------------------------------------- reflectors24. Point focus collectors use ---------------------------------------------- reflectors25. Concentration ratios of paraboloidal dishes can be ------------------------------------------26. Sun-tracking is done for concentrating collectors using -------------------------------------27. Point focus collectors need sun tracking in ---------------------- planes.28. A number of concentrating collectors arranged over a large area is called --------------------------

system.29. Collecting solar energy using many collectors at one place is called -------------------------------30. The efficiency of flat plate collectors is ----------------------------------------31. Solar radiation can be measured using ------------------------------------------------32. ----------------------------------- can be used for latent heat storage of solar energy.33. Solar ponds can heat water at bottom layers upto a temperature of --------------------------34. By using salt with varying concentration levels, solar ponds arrest ------------------------------------35. The efficiency of a PV cell is generally in the range of --------------------------------------36. Solar energy received by earth is about ---------------------------- times our present total

consumption of energy37. The potential of wind energy in the world is about -----------------% of our total energy

requirement.38. Two types of vertical axis windmills are ------------------------- & ------------------------- type39. The maximum efficiency of windmill (Betz limit) is ----------------------------%

40. The efficiency of vertical axis windmill is ------------------------ than that of horizontal axis mill.41. ----------------------------- type vertical windmill is not self starting.42. The aerodynamic component responsible for power generation in a horizontal axis windmill

is ------------------------------------------ (lift/drag).43. The suitable range of wind velocity for wind turbine is between ------& -------- m/sec.44. Tethering (pitch) control is required for horizontal axis wind turbines because

----------------------------------------------------------------------------------------45. Yaw control is required for horizontal axis wind turbines due to

-----------------------------------------------------.46. Vertical axes wind turbines do not require pitch and yaw controls because

-----------------------------------------------------------47. If wind velocity doubles, the output of wind mill increases ------------------------ times.48. If the diameter is doubled, the output of windmill increases ------------------------ times.49. Two countries which use wind turbines most are ---------------------------------------50. Two countries which used windmills extensively before 1900 AD are

------------------------------------51. Large windmills can have blade diameters up to ----------------------- metres.52. Pyranometer is used for measuring ------------------------------------------------------------53. Pyrheliometer is used for measuring -------------------------------------------------------------54. Average temperature on earth’s surface is -------------------------------55. Average daily global solar radiation in computed using --------------------------- equation

Hints: 1. Nuclear fusion2. 5762oK 3.15.2oC 4.Stratosphere 5. 1353 W/m2

6. Solar insolence 7. <0.39 micron 8.>0.78 micron 9.46% 10.March 21 11. Sept 21 12. June 21 13.Dec 21 14.12700 km 15.13.92 X 105 km 16.1.5 X 108 km 17.Ecliptic 18.23.45o 19.equinoxes 20. Winter solstice 21. 22.7 MJ/m2 23) parabolic 24) paraboloid

25) more than 1000 26) heliostats 27) two 28) distributed collector system 29) solar farm 30) 30-50% 31) pyrheliometer 32) paraffin, Glauber salt33) 95oC 34) heat convection 35) 20-25% 36) 10,000 37) 20% 38) Savonius and Darrieus 39) 59.3% 40) less 41) Darrieus 42) lift 43) 5 to 25 m/s 44) wind velocity is more at the highest point of the mill and less at the lowest point 45) changes in wind direction 46) direction of wind does not affect working of vertical axis mill 47) eight 48) four 49) USA, Germany 50) Denmark, Holland

51) 130 52)Total solar radiation (beam + diffuse) 53) Beam radiation from sun 54)14.5o C

55) Angstrom’s equation