What occurs when the tip of the umbra falls on the earth?
Partial solar eclipse
Partial lunar eclipse
Annular solar eclipse
None of these
Rays of light always travel in a straight line.This phenomenon is called:
Total internal reflection
Rectilinear propagation
Scattering of light
A glowing electric bulb is an example for:
Point source of light
Extended source of light
Ray of light
Radius of curvature, r =
f/2
2f
2/3 f
f
