The primary way to distinguish between concave and convex mirrors is by observing the direction in which their reflecting surfaces are curved.
Therefore, a mirror with a surface curving inward is concave, and one with a surface curving outward is convex.
Two convex lenses have focal lengths of 50 cm and 25 cm, respectively. If these two lenses are placed in contact, then the net power of this combination will be equal to
The refractive index of crown glass is close to 3/2. If the speed of light in air is c, then the speed of light in the crown glass will be close to
Tyndall effect is a phenomenon of