It's our report.

2. - is an electronic system of transmitting
pictures and sounds over a wire or through the
air
- is a picture machine used in education
and information distribution

3. CRT ( Cathode Ray
Tube) Television

4. The flat end of a picture tube (the
screen) is covered with phosphor salts.
Phosphor is a substance that emits light
when given energy.
At the back of the picture tube is an electron
gun. The electron gun projects a beam onto
the phosphorescent (phosphor-covered)
screen.

6. The beam goes across the screen in a leftto-right direction 525 times. This occurs 30
times every second, just as when the camera
scanned the picture elements. Because each
scene is replaced 30 times every second, your
brain interprets these rapid changes as a
continuously moving image.
The beam excites the phosphor salts and
makes them glow. These growing pixels create
the image you see.

8. A color picture tube has three electron
guns that sweep across the flat surface of the
tube. One gun is used for each of the primary
colors of light-red, green, and blue. The surface
of the color picture tube is covered by groups
of red, green, and blue phosphor pixels, which
will make up the color image.

10. It is extremely important that the
appropriate electron gun hits the correct
phosphors. Most televisions have a masking
guide that directs the beams to the correct
phosphors. The beams excite the phosphors
to create the color picture you see on the
screen.

12. The force exerted by a magnetic field on a
current-carrying wire is a result of the forces on
the individual charges that make up the current
flow. The charged particles do not have to be
confined to a wire, but can move across any
region as long as the air has been removed to
prevent collisions with air molecules.

14. The picture tube, or cathode ray tube, in a
television set uses electrons deflected by
magnetic fields to form the pictures on the
screen. In the tube, electric fields pull electrons
off atoms in the negative electrode or cathode.
Other electric field gather, accelerate, and focus
the electrons into a narrow beam. Magnetic fields
are used to deflect the beam back and forth and
up and down across the screen of the tube. The
screen is coated with a phosphor that glows
when struct by the electrons, producing the
pictures.