A) reproduction of films from the cinema films
B) reproduction of sound from the cinema films
C) automatic switching of street light
D) both (a) and (b)
Correct Answer: D
Solution :
The use of photocells (solar cells) has been of public and scientific interest for many years. It collects the suns energy, then using the photoeletric effect it converts solar energy into electrical energy. Hence, used in automatic switching of street light. The photocell also produces an electric current when exposed to light. Changing current is needed to produce a sound in speaker. Used in reproduction of sound in cinema halls.
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