In the near future, people in some parts of the world will watch a new kind of television. It is called the high definition television or the HD-TV. The main difference between an HD-TV and a normal television is the picture. It is more clear and detailed. This is because the HD-TV has many more points and lines that make a television image. Every color television picture contains thousands of red, green and blue points. They all come together as an image in the eye of the person watching. The points are organized in lines that go across the television screen. There are more than five hundred lines in a normal television. The HD-TV has two times as many. To get this clear picture, you must have a big screen. Experts say people using a small screen will see little difference. The HD-TV also has clear sound. It is like the sound on a CD. All these improvements make an HD-TV very costly. One kind in Japan now sells for more than twenty thousand dollars .A major problem with the HD-TV is its broadcast signal(.The signal is bigger than normal because it carries more electronic information. How many lines does an HD-TV have?
Over 250 More than 500 More than 1,000 About 250