Which of the following situations is photoelectric effect employed? I. Automatic devices for switching on light at dusk II. Automatic doors in departmental stores III. Automatic devices for switching on air conditioners IV. Automatic voltage stabilization
A. I, II and IV only
B. I, III and IV only
C. III and IV only
D. I and II only
Answer:A
Which of the following situations is photoelectric effect employed? I. Automatic devices for switching on light at dusk II. Automatic doors in departmental stores III. Automatic devices for switching on air conditioners IV. Automatic voltage stabilization
A. I, II and IV only B. I, III and IV only C. III and IV only D. I and II only