An object is kept at the centre of curvature of a concave mirror. The position and nature of the image formed is 

($F =$ principal focus, $C =$centre of curvature, $P =$ pole)

Focal length of one convex mirror is $3 \mathrm{m}$ and object distance is $5 \mathrm{m}$, then find the image distance.

A concave mirror of focal length 15cm forms an image. The position of the object when the image is virtual and linear magnification is 2 is.

In the following diagram ‘$M$’ is a mirror and ‘$P$’ is an object and ‘$Q$’ is the magnified image of ‘$P$’ formed by the mirror. The mirror ‘$M$’ is a:

Which effect is responsible for blue colour of smoke?

If a mirror forms erect image for objects placed between pole and focus, and it forms real-inverted image for object placed anywhere between focus and infinity, then the mirror is: