SENSITIVITY OF THE PHOTO ELECTRIC CELL

To understand more clearly the applications of the photoelectric cell it might be well to consider its amazing and positively breathtaking sensitivity which has practically no limit. Nor is there any practical limit to the speed with which this remarkable invention reacts. The slightest variation in current a variation so slight and so rapid that the human mind is incapable of perceiving it is faithfully recorded by the photoelectric cell. If there were any way of comparing sensitivity with volume, we might well say that its sensitivity with volume, we might well say that its sensitivity and its speed of reaction are as keen and as rapid as the electron is small.

This is equally true of the reactions of the electromagnet. It would be well for us to think of vibrations and variations in electric current not as something that we can count, not something that we can see, but as something that takes place instantaneously. If we bear this in mind while discussing the telephone, the radio, talking pictures and television, it will help us to understand why certain things happen as they do. We can use this photoelectric cell in many ways like solar energy into electrical energy and fire alarm.