When we stand in sunlight we feel the heat due to the presence of
Infrared radiation
Ultraviolet radiation
Radio waves
Electromagnetic radiation
Refractive index of Glycerine is
1.33
1.44
1.47
1.36
When the object is beyond 2F, the image formed is
at F
at 2F
Between F and 2F
at infinity
Rainbows are formed due to
Diffraction of light
Dispersion of light
Convergence of light
Divergence of light
Which of the following joins the centres of curvatures of the two spherical surface of the lens?
Centre of curvature
Radius of curvature
Principal axis
Optical centre
Ultraviolet rays help to produce vitamin
Vitamin-A
Vitamin-B
Vitamin-C
Vitamin-D
The defect of hypermetropia may be corrected by using
Concave lens
Convex lens
Prism
None of these
Which of the following help us to see tiny objects which are magnified many more times than a simple microscope ?
Compound microscope
Telescope
Stethoscope
The distance between the optical centre and the principal focus of a lens is known as
Principal focus
Focal length
A medium is said to be optically dense if the speed of light become
Faster
Slower
Not changed
