Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Video Screens and Light 
Name: Joe
Status: Student
Grade: 6-8
Location: IL
Country: United States
Date: Summer 2009
Question:
How do screens such as TV's, liquid crystals, plasmas, and computer screens light up?


Replies:
Hi,

In answer to the 4 examples you asked about:

1. Vacuum Tube TVs: on the inside of the screen, there is an array of microscopic phosphor dots that emit light when they are hit by the three electron guns in the picture tube. More information about how a picture tube works can be found here:

http://www.ehow.com/how-does_4565056_cathode-ray-tube-work.html

2. Liquid Crystal (LCD) screens: These have a backlight (a light source located behind the LCD) that illuminates the screen from behind, through an LCD color filter.

3. Plasma Screens generate their own light as a result of a high voltage discharge. More information can be found here:

http://electronics.howstuffworks.com/plasma-display.htm

4. Computer screens use one of the three technologies explained above.

Regards,

Bob Wilson


Click here to return to the Engineering Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory