A mobile phone lies along the princip axis of a concave miror.Show,with the help of a suitable diagram,the rformatrion of its image.Explain,wy magnification isnot uniform.

A 5 cm long needle lies along the principal axis axis of a concave miror of focal length 20 cm in such a way that the end closer to the pole is 40 cm from it.Find the length of the image of the needle formed by the mirror.

The figure TBQ 9.38 shows an equiconvex lens (of refractive index 1.50) in contact with a liquid layer on top of a plane mirror. A small needle with its tip on the principal axis is moved along the axis until its inverted images if found at the positions of hte needle. The distance of the needle from the lens is measured to be 45.0 cm. The new distane is measured to be 30.0 cm. What is the refractive index of the liquid?