#1 The position, relative size and nature of the image formed by a concave lens for an object placed at infinity are respectively
From the ray diagram, it is very clear that the image of the object placed at infinity from a concave lens is virtual diminished and at the focus of the lens.
#2 The upper and lower portions in common type of bi-focal lenses are respectively
The upper and lower portions in common type of bifocal lenses are concave and convex respectively.
#3 In the phenomenon of dispersion of light, the light wave of shortest wavelength is
In the phenomenon of dispersion of light, the light wave of shortest wavelength is slowed down and refracted the most.
#4 In an observation, α-particles, β-particles and γ-rays have same energies. Their penetrating power in a given medium in increasing order will be
γ – rays are the most penetrating rays
β – particles are moderately penetrating and
α – particles are least penetrating.
#5 Contact lenses are made from
Contact lenses are made from lucite. It is a polymer of methyl methacrylate. The other names of lucite are plexiglass, acrylate and Perspex.