An object of height 3.6 cm is placed normally on the principal axis of a concave mirror of radius of curvature 30 cm . If the object is at a distance of 10 cm from the principal focus of the mirror, then the height of the real image formed due to the mirror is

Monochromatic light of wavelength $6000 \mathop {\rm{A}}\limits^{\rm{o}} $ incidents on a small angled prism. If the angle of the prism is $6^{\circ}$, the refractive indices of the material of the prism for violet and red lights are respectively 1.52 and 1.48 , then the angle of dispersion produced for this incident light is

A compound microscope has an objective of focal length 1.25 cm and an eyepiece of focal length 5 cm separated by a distance of 7.5 cm . The total magnification produced by the microscope when the final image forms at infinity is

The property of light that explains the formation of coloured images due to thick lenses is