The point at which at which light rays passing through a lens come together
A lens that is thicker at the edges than it is in the middle
The light sensitive area at the back of the eye
A mirror that curves out ward
An instrument for viewing distant objects that used a curved mirror at the of it's tube to gather light
A microscope that uses a signal lens to magnify objects
A viewing instrument that magnifies objects thousands of times by using a beam of electrons
Please allow access to your computer’s microphone to use Voice Recording.
We can’t access your microphone!
Click the icon above to update your browser permissions and try again
Reload the page to try again!
Press Cmd-0 to reset your zoom
Press Ctrl-0 to reset your zoom
It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.
Your microphone is muted
For help fixing this issue, see this FAQ.