A lens surface that is______________bulges outward from the lens, while a lens surface that is_______________is depressed into the lens.

The SCR is a

Although they last no longer than a fraction of a second, voltage variations can cause problems with sensitive electronic equipment. Variation in voltage causes digital clocks to blink and timers to be thrown off schedule.
Computers are especially

The flywheel is attached to the

About three-fourths of the Earth's surface is covered with water. Of these 336 million cubic miles of water, most (97.2 percent) is found in the oceans and is salty. Glaciers at both poles contain another 2 percent of the total amount. Less than 1 percent (0.8 percent) is available as fresh water for people to use--and much of that is not near the people who need it the most.
The amount of fresh water available for people to use is