Shadow Power 24

If the object is moved from eyesight, the sense of vision does not go away immediately. It remains for about 0.03s. This period is called persistence of vision.

Iris is a flat, coloured, ring-shaped membrane behind the cornea of the eye.

Radiation is the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles that cause ionization.

Rainbow is an arch of colours visible in the sky, caused by the refraction and dispersion of the sun’s light by rain or other water droplets in the atmosphere.

When parallel rays parallel to the principal axis passes through the lens they either converge to or appear to diverge from a point after refraction which is called the principal focus of the lens.

A real image is when the light rays actually are brought to a focus at the image position after reflected or refracted from the lens.

Snell’s law states that when light enters obliquely into a transparent medium from another transparent medium, then for a fixed pair of media and for a fixed colour of light the ratio of the sine of the angle of incidence to the sine of the angle of refraction always remains constant.

Infrared light comes of TV remote control which cannot be seen with the naked eye.