question_answer

      Which of the following statement is/are the applications of photovoltaic cells?                             

A. They are used to detect opacity of solids, defects materials.

B. They are used to switch on and off the street automatically

C. They are used to compare illuminating power of two sources.

D. To control temperature in furnaces and chemical reactions

A) B and C                

B)        B, C, D

C) A, B, C                 

D)        All of these