The centre of the sphere whose part is the lens surface, is called the ____________ of that surface of the lens.
None of these
Centre of curvature
Radius of curvature
Principal foci
The power of a lens is +2.0 D. Find its focal length and state what kind of lens it is
5 cm, convex
50 cm, convex
5 cm, concave
50 cm, concave
A convexo - concave lens is
Thick at the centre and thin at the periphery
Thin at the centre and thick at the periphery
Thick at the centre with one surface plane
A con cavo-convex lens is
Thin at the centre with one surface plane
A ray of light directed towards the optical centre of a lens, after refraction:
is reflected black
Passes through the focus
Be comes paralll to the principal axis after refraction
Passes undeviated
Which is diverging lens?
All of these
Concavo convex lens
equi-convex lens
Equi concave lens
A beam of light incident on a convex lens parallel to its principal axis converges at a point on the principal axis. Name the point.
First focus
Optical centre
Second focus
On reducing the focal length of a lens its power
Doesnot change
Nothing can ve said
Decreases
Increases
A ray of light incident on a lens parallel to its principal axis, after refraction passes through.
The centre of curvature of its second surface
Its first focus
Its optical centre
its second focus
Which lens is diverging?
Convex lens
Both (a) and (b)
Concave lens
