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Lighting Solution

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Rural Technology

Selection of proper lighting device is very much important for optimum usage of solar energy. Following is comparison of different light sources.

Electric lamp.jpg

Sr.No. Parameter

Kerosene Lantern Incandescent Compact

Fluorescent WLED 1 Efficiency (Lumens/watt) 0.03 5-18 30-79 25-50 2 Rated Life (Hours) Supply of kerosene 1000 6500-15000 50000 3 Durability Fragile& Dangerous Very Fragile Very Fragile Durable 4 Power consumption 0.04-0.06 Liters/hour 5W 4W 1W

From the table it is clear that White Light Emitting diodes (WLED) gives maximum lumens per watt. ( Lumens is unit to measure light intensity). This means we save almost 1/5 of energy compared to incandescent bulb if LEDs are used.

Intext Questions  :

Fill in the blanks. 1) The solar cells are made up of ………… …….. 2) A solar cell is a sandwich of …………..and ……………….. silicon. 3) A solar cells are connected in series – parallel arrays ,called ……………. 4) Solar energy system does not work during …………. 5) Energy packet is also called as………… 6) ……….cells dust is hazardous for the health. 7) Requires higher capital for the manufacturing of ………… 8) ………… is method by which ……… produce their food.

WHAT HAVE YOU LEARNT

• A solar cell is made of a semiconductor. • What is a semiconductor. • When sunlight shines on the cell, photons collects the energy & transfers to the neighboring cell. • Flowing around the circuit, the electrons make the lamp light up. • Selection of the lighting source.

TERMINAL QUESTIONS :

Why the diode is used in connection with solar panel and battery ? 1) State the advantages of solar cells ? 2) State the disadvantages of solar cells ? 3) What is the basic principal of solar lightening system?


ANSWERS TO INTEXT QUESTIONS

1. Solar panel 2. n type & p type silicon cells. 3. Solar Panel 4. Night 5. photon 6. silicon 7. solar panels 8. photosynthesis , plants

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