MadSci Network: Physics
Query:

Re: Why does a TV screen at night seem to glow right after you turn it off??

Date: Wed Dec 8 15:31:58 1999
Posted By: Judith E. Bush, Staff, Educational Technology Programs, Franklin Institute Science Museum
Area of science: Physics
ID: 941148815.Ph
Message:

A TV screen uses the same technology as a computer monitor; the technical
term is a CRT (Cathode Ray Tube). Inside the monitor box or TV console is a
large vacuum tube with three electron guns (or one in the case of
monochrome sets) at one end. The screen is at the other end and is coated
with a grid of phosphorescent dots. When the electrons hit the dots, they
glow. That glow must last until the gun sweeps to that point on the screen
again, so it will last after then gun is turned off.

The following is a response to a similar question and provides much more
technical detail about the glow of the phosphor dots.
 http://flax.ims.uconn.edu/~jon/REPAIR/F_tv_repairf.html#TVREPAIRF_007

These are general explanations of how a CRT is constructed.
 http://whatis.com/crt.htm http://www.pctechguide.com/06crtmon.htm

Cheers,

judith

Judith E. Bush                                          jbush@fi.edu
The Franklin Institute Science Museum           New Media Specialist
222 N. 20th Street                                  1 (215) 448-1236
Philadelphia, PA 19103-1194 USA                    AOL IM judielaine





Current Queue | Current Queue for Physics | Physics archives

Try the links in the MadSci Library for more information on Physics.



MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci


MadSci Network, webadmin@www.madsci.org
© 1995-1999. All rights reserved.