Question

Solar cell operates on the principle of
A. Diffusion
B. Recombination
C. Photovoltaic action
D. Carrier flow

Answer 1

Solar cell is used to convert light energy to electrical energy. Concept involved is the photovoltaic effect. Photo means light and voltaic means electricity. Thus, electricity is produced from light.

Complete answer:
Solar cells are also known as Photovoltaic cells. It is an electrical device which converts light energy directly into electricity by photovoltaic cells. A solar cell is made up of two types of semiconductors, called p-type and n-type silicon. The p-type silicon is produced by adding atoms of boron or gallium.

Boron or gallium is used in p-type semiconductor as they have one less electron in their outermost shell than silicon. As boron has one less electron than is required to form bonds with the silicon atoms, an electron vacancy or hole is created. The n-type semiconductor is produced by adding atoms of phosphorus. Phosphorus is used in n-type semiconductor as they have one more electron in their outermost shell than silicon.

As phosphorus has one extra electron that is not involved in bonding with silicon atoms, it is free to move inside the silicon structure. A p-n junction is formed by placing p-type electrons and n-type semiconductors next to one another. As the p-type semiconductors have deficiency of one electron so they attract electrons from n-type to stabilize itself. Thus, due to flow of electron electricity is generated.

When sunlight hits the semiconductor, an electron gets excited and moves towards the n-type semiconductor. This causes more negatives in the n-types semiconductors and more positives in p-type, thus generating a higher flow of electricity. This is known as the photovoltaic effect.

Hence, the correct answer is option C.

Note: Solar cells are pollution free and last for a long period of time and have no maintenance cost. Solar cells are used in light meters, used to charge batteries, used in power calculators and wrist watches too.