I. Give reasons for the following.
1. The image formed by a plane mirror cannot
be obtained on a screen.
2. Plane mirrors are used as dressing mirrors.
3. Why does a white drawing sheet appear
white when seen in white light but appear
blue when seen in blue light?
4. Why does your school blackboard appear
black?
5. For regular reflection, the reflecting surface
should be smooth and polished.
6. How can we see objects situated near us?
Answers
1) A virtual image is formed when reflected rays appear to meet. Such images cannot be obtained on screen. Plane mirrors, convex mirror and concave lens always forms virtual image.
2)Uses of plane mirror
Plane mirrors have many uses. Some of them are, Mirrors are used to see our own images while dressing. Plane mirrors are used in interior designing to create an illusion of depth.
3)Colour of any object is by the colour of light it reflects i.e if white light is incident on the object,it will reflect blue color.so it will appear blue
4)Actually a black board has all colours in light or white light . So when light falls on it board absorbs all colours because all are present so no light is reflected back . That is the case when board has all colours and so it will appear black as it absorbs all colours of light that fall on it .
5)Irregular reflection occurs when parallel rays of light are incident on an irregular or rough surface and after reflection emerge in different directions. ... Regular reflections occur from smooth or polished surfaces
6)The light rays propagate in a straight line. When any object comes in its path of propagation, it bends back or reflects back alter striking the object. The reflected rays come to our eyes and we see the objects around us.
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