SECTION B – Short Answer Questions

(35 Questions)

1. Define energy.

Model Answer: Energy is the capacity to do work.

2. State the first law of thermodynamics.

Model Answer: Energy can neither be created nor destroyed; it can only be converted from one form to another.

3. What are renewable energy sources? Give two examples.

Model Answer: Renewable energy sources are naturally replenished sources of energy. Examples: solar energy and wind energy.

4. Why is electrical energy considered convenient?

Model Answer: It is easy to transmit, distribute, control, and use for various domestic, commercial, and industrial purposes.

5. Differentiate between conductor and insulator.

Model Answer: Conductors allow free flow of electrons, whereas insulators do not allow electrons to move easily.

6. What is electric current?

Model Answer: Electric current is the flow of free electrons through a conductor.

7. What is voltage?

Model Answer: Voltage is the potential difference or force that causes current to flow through a conductor.

8. What is resistance?

Model Answer: Resistance is the opposition offered by a material to the flow of electric current.

9. Write the unit of current, voltage, resistance, and power.

Model Answer: Current – Ampere, Voltage – Volt, Resistance – Ohm, Power – Watt.

10. What is a solar cell?

Model Answer: A solar cell is a semiconductor device that converts sunlight directly into DC electricity by photovoltaic effect.

11. State two advantages of solar PV technology.

Model Answer: No moving parts, low maintenance, works with diffuse radiation, suitable for varying power requirements.

12. State two limitations of solar PV technology.

Model Answer: Low efficiency and intermittent nature of solar energy.

13. What is photovoltaic effect?

Model Answer: It is the phenomenon in which sunlight falling on a semiconductor material generates electrical voltage and current.

14. What is the typical voltage of a single solar cell?

Model Answer: About 0.5 to 0.6 V.

15. Why are many solar cells connected together?

Model Answer: A single cell produces very low power, so many cells are connected to obtain useful voltage and power output.

16. What is a solar module?

Model Answer: A solar module is an assembly of multiple solar cells connected together in a protective framework.

17. What is the role of EVA in a solar module?

Model Answer: EVA encapsulates the cells, provides protection, and allows good radiation transmission.

18. What is series connection of solar cells?

Model Answer: In series connection, the positive terminal of one cell is connected to the negative terminal of the next cell so that voltage adds up.

19. What is a solar charge controller?

Model Answer: It is a device that regulates voltage and current from the solar panel to safely charge the battery.

20. Why is a charge controller needed in off-grid systems?

Model Answer: It protects the battery from overcharging, over-discharging, reverse current, and unsafe charging conditions.

21. Mention any two functions of a solar charge controller.

Model Answer: Battery protection, optimized charging, load control, system safety, and battery maintenance.

22. What is a solar inverter?

Model Answer: A solar inverter is a device that converts DC power from solar panels or batteries into AC power.

23. Why is an inverter needed in solar systems?

Model Answer: Most household appliances and grid systems operate on AC, while solar panels produce DC.

24. What is a rectifier?

Model Answer: A rectifier is a device that converts AC into DC.

25. What is a DC-DC converter?

Model Answer: It is a device used to convert one level of DC voltage to another level.

26. Define battery.

Model Answer: A battery is an electrochemical device that stores chemical energy and converts it into electrical energy.

27. What are the two terminals of a battery?

Model Answer: Positive terminal and negative terminal.

28. What is anode in a battery?

Model Answer: The anode is the electrode that releases electrons during discharge and is negative.

29. What is cathode in a battery?

Model Answer: The cathode is the electrode that absorbs electrons and is positive.

30. What is electrolyte in a battery?

Model Answer: Electrolyte is the medium that enables ion movement inside the battery.

31. What is electrical load?

Model Answer: An electrical load is any device that consumes electric current and converts it into useful form such as light, heat, or motion.

32. Why is load calculation important in solar system design?

Model Answer: It helps determine the required system size, battery capacity, inverter size, and energy consumption pattern.

33. Write the formula for energy consumed.

Model Answer: Energy consumed = Power × Time.

34. What is meant by 1 unit of electricity?

Model Answer: One unit of electricity is equal to 1 kilowatt-hour (1 kWh).

35. What is a solar feasibility study?

Model Answer: It is a detailed assessment of a site to determine whether a solar energy project is technically, economically, and environmentally viable.

36. What is meant by conventional energy sources?

Model Answer: Conventional energy sources are traditional sources widely used for a long time, such as coal, petroleum, natural gas, and in some contexts nuclear energy.

37. Name any four forms of energy.

Model Answer: Thermal energy, light energy, electrical energy, and mechanical energy.

38. Why is access to reliable energy important for development?

Model Answer: Reliable energy supports technological growth, economic development, productivity, and improved quality of life.

39. What is a semiconductor?

Model Answer: A semiconductor is a material whose electrical conductivity lies between that of a conductor and an insulator.

40. What is meant by a neutral atom?

Model Answer: A neutral atom has equal numbers of electrons and protons.

41. Define ampere.

Model Answer: Ampere is the unit of electric current. It represents the amount of charge flowing per second through a conductor.

42. What is meant by potential difference?

Model Answer: Potential difference is the difference in electric potential between two points that causes current to flow.

43. On what factors does resistance depend?

Model Answer: Resistance depends on material composition, length, cross-sectional area, and temperature.

44. Write any two uses of solar PV technology.

Model Answer: Solar street lighting and water pumping. Other examples include satellites, battery charging, household appliances, and remote communication systems.

45. What is meant by diffuse radiation?

Model Answer: Diffuse radiation is sunlight scattered by the atmosphere that reaches the surface from multiple directions.

46. What is meant by electron-hole pair generation in a solar cell?

Model Answer: When photons are absorbed by the semiconductor, energy is transferred to electrons, creating free electrons and corresponding holes.

47. What is the significance of band gap in solar cells?

Model Answer: The band gap determines how the semiconductor absorbs light and how effectively photons can generate charge carriers.

48. Differentiate between solar cell and solar module.

Model Answer: A solar cell is a single photovoltaic device, while a solar module is an assembly of many solar cells connected together to deliver useful power.

49. What is a solar panel?

Model Answer: A solar panel is the field-installable unit that includes the solar module and associated structural/junction arrangements.

50. State two characteristics of solar PV modules.

Model Answer: They are safe and reliable, and they have long service life, typically around 20 to 30 years.

51. What happens to voltage when solar cells are connected in series?

Model Answer: The voltages of individual cells add together.

52. Why is safe battery charging important?

Model Answer: Safe battery charging prevents overheating, damage, reduced life, and unsafe operating conditions.

53. What is load control in a charge controller?

Model Answer: Load control is the function by which some controllers manage connected loads to prevent deep discharge and improve system performance.

54. What is reverse current in a PV system?

Model Answer: Reverse current is the unwanted flow of current from the battery back to the solar panels when the panels are not generating power.

55. What is a power converter?

Model Answer: A power converter is a device that converts electrical power from one form to another, such as AC to DC, DC to DC, or DC to AC.

56. Why are rectifiers used in computers?

Model Answer: They convert AC supply into DC because internal electronic components require DC power.

57. Give one example where a DC-DC converter is useful in a solar system.

Model Answer: It is useful when the DC voltage from the PV system must be stepped up or stepped down before being supplied to an inverter or load.

58. Why do most home appliances need inverter output?

Model Answer: Most home appliances are designed to operate on AC power, whereas solar panels and batteries provide DC.

59. What is meant by battery discharge?

Model Answer: Battery discharge is the process in which stored chemical energy is converted into electrical energy and supplied to the load.

60. What is meant by battery charge cycle?

Model Answer: A charge cycle involves charging the battery and then discharging it during use.

61. Name the basic building blocks of a battery.

Model Answer: Anode, cathode, and electrolyte.

62. Why is load estimation necessary before sizing a solar system?

Model Answer: It helps determine the required capacity of PV modules, batteries, charge controllers, and inverter.

63. What is meant by intermittent load?

Model Answer: Intermittent load is a load that operates occasionally or for shorter periods, not continuously.

64. Define kilowatt-hour.

Model Answer: Kilowatt-hour is the energy consumed when 1 kilowatt of power is used for 1 hour. It is equal to one unit of electricity.

65. What is meant by solar potential?

Model Answer: Solar potential refers to the amount of solar energy available at a location that can be converted into useful electricity.

66. Why is solar resource assessment important before project installation?

Model Answer: It helps estimate expected energy generation, system size, viability, and return on investment.

67. What is site suitability in a feasibility study?

Model Answer: Site suitability means evaluating whether a particular site has the right conditions for solar installation, such as sunlight, space, and accessibility.

68. What is meant by grid connectivity in a solar feasibility study?

Model Answer: It refers to the ability of the solar project to connect to the electrical grid and export or manage generated power.

69. What is the importance of risk assessment in solar projects?

Model Answer: Risk assessment identifies technical, financial, environmental, or regulatory issues that may affect project success.

70. Why is solar energy called intermittent?

Model Answer: Solar energy is called intermittent because it depends on sunlight availability and is not constant during night or poor weather.