Optics (Physics) Part-II

The colour of the sky for an astronaut is black. It is because of the fact that in the space there is no atmosphere. In space, there are no air particles against which the sunlight can strike, get reflected or scattered. Hence, astronaut see everything black.

The colour of the sky for an astronaut is black. It is because of the fact that in the space there is no atmosphere. In space, there are no air particles against which the sunlight can strike, get reflected or scattered. Hence, astronaut see everything black.

The sea looks blue due to reflection of sky and scattering of light by the drops of water. Light scattered as it passes through air or water. Since blue light has a short wavelength, it scatters most easily.

The colour we see on the surface of an object is not actually the colour in that surface. If a surface looks green, it means that it absorbs all colours of the spectrum except green. It looks black to our eyes in case no colour is reflected. If an object is white it reflects all light.

The colours that we see when observing a soap film are caused by interference of light reflecting off of two nearby surfaces the outer surface and the inner surface.

Interference patterns are created when two reflected waves line up in phase or out of phase. White light is a mixture of all the wavelengths of the visible spectrum and the interference enhances some wavelengths and diminishes others, creating visible colours.

The specific wavelengths that are enhanced or diminished are determined by the thickness of the film and its index of refraction.

When the position of object is between infinity and pole (P) of the convex mirror, then the image will be formed between the pole (P) and the focus (F) behind the mirror. The image thus formed is diminished, virtual and erect.

When light passes through a convex lens, it converges or comes together at a focal point. In this case, the convex lens has a focal length of 20 cm. When the lens has a large number of thin black strips on its surface, these strips will block or absorb some of the incident light.

As a result, less light will reach the focal point and form the image. Hence, thin black strips on the surface of a convex lens will only reduce the intensity of the light but will not cast any shadow on the image, as it is quite thin. Thus, option (a) is the correct answer.

A convex mirror gives a much wider field of view of the traffic at your back than a plain mirror of the same size. It always forms an erect and diminished image and they also have a wider field of view as they are curved outwards.

A convex mirror gives a much wider field of view of the traffic at your back than a plain mirror of the same size. It always forms an erect and diminished image and they also have a wider field of view as they are curved outwards.