If you are referring to "light" as in a "light device," "the light," "a light bulb," etc. you can use the general sign for light that uses the dominant hand in an "8" handshape under the chin.

When discussing colors you can often express the concept of "light" by doing the signs with a smaller, more delicate movement, with a bit of an "ooh" facial expression.

HEAVY: LIGHT: As in "lightweight" or "light in color" For more "light" related signs, visit the LIGHT page

The sign above would be used for old upright "desktop" style computers. You should modify the angle and movement to match wherever the "on button" is on your computer or device.

ASL - American Sign Language: free, self-study sign language lessons including an ASL dictionary, signing videos, a printable sign language alphabet chart (fingerspelling), Deaf …

You could use the fingerspelled version of "off" to turn off an appliance or a computer, but another common and very clear sign is the sign for "power off." This is a good version for such …

American Sign Language: "shine" SHINE / RADIATE / SPARKLE In this sign you use your straight middle fingers (bent forward at the large knuckle) to represent rays of light reflecting …

Most of the time you do NOT need to use the "on" sign. For example, to sign "The party will be on Tuesday" you would sign PARTY with your brows up, and then "TUESDAY" with an affirming …

Students of ASL develop an understanding of the nature of language, including grammar, and culture and use this knowledge to compare languages and cultures and to expand insight into …

If you mean "shut" as in "shut down," or "shut off" then use the "power off" sign. Start with your fingers spread and then lower your arms just a bit while bringing your fingers and thumb …