THESE 3 QUESTIONS PLZ :

1- Close your left eye and hold your hands in front at arm's length, with your palms facing front so that the back of your hand is facing you. Stick your thumbs and index fingers out (make an L), make the two thumbs touch at the tips. As you look at your left index fingertip with your right eye, tilt your right index finger so that you cannot see the nail on your right index finger. Explain why your right index fingertip "disappears".

2-. When you point a small flashlight at your eye you can sometimes see the blood vessels of your retina. Explain why we do not normally see the blood vessels but do with the flashlight.

3- When the pupil is very small, it acts as a pinhole. Explain how that would affect the vision of near-sighted and far-sighted individuals under bright versus dim light.