Which of the following phenomenon is not explained by Huygen's construction of wavefront?

If two mirrors are kept inclined at 60° to each other and a body is placed at the middle, then total number of images formed is :

The hypermetropia is a

Interference is possible in

Focal length of a convex lens of refractive index 1.5 is 2 cm. Focal length of lens when immersed in a liquid of refractive index of 1.25 will be :

An astronomical telescope of ten fold angular magnification has a length of 44 cm. The focal length of the objective is :

For the given incident ray as shown in figure, the condition of total internal reflection of the ray will be satisfied if the refractive index of block will be

If f_v and f_n are the focal lengths of a convex lens for violet ad red light respectively and F_V and F_R are the focal lengths of concave lens for violet and red light respectively, then we have :

A telescope has an objective lens of 10cm diameter and is situated at a distance of one kilometre from two objects. Find out the minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is 5000 Å.