Inventing the television
Fill in the gaps using the following words:
photoelectric effect, conducts, concept, value
In the 1870s scientists discovered that the element selenium had some unusual properties. Experiments showed selenium is sensitive to light. It __________________ different amounts of electricity, depending on how much light falls on it.
This __________________ gave scientists an idea. They realised they now had a way of changing light into an electric signal. This meant they could create a system that could transmit pictures over distances.
The theory was simple. First the picture would be broken down into small pieces. Next, each piece would be given a __________________ for brightness. This information would be transmitted and used by the receiving machine to reconstruct the picture.
The concept was dubbed television: a combination of the Greek word tele meaning far and the Latin word vision meaning sight.
