Q. Give three applications of photoelectric cells.
(i) Photoelectric cells are utilized for reproducing sound in cinematography.
(ii) They are utilized for controlling the temperature of furnaces.
(iii) Photoelectric cells are utilized for automatic switching on and off the street lights.
(iv) Photoelectric cells are utilized in the study of temperature and spectra of stars.
(v) Photoelectric cells are as well used in obtaining electrical energy from sunlight during space travel.
(vi) These cells are utilized in instruments measuring light illumination.
(vii) These cells are utilized in opening and closing of door automatically.
(viii) Photoelectric cells are utilized in burglar alarm and fire alarm.