The sky would appear red instead of blue if ____.
atmospheric particles scatter blue light more than red light
atmospheric particles scatter all colours equally
atmospheric particles scatter red light more than the blue light
the sun was much hotter
Sir C.V. Raman was awarded Nobel Prize for his work connected with which of the following phenomenon of radiation ____.
scattering
diffraction
interference
polarization
In absorption spectrum of Na the missing wavelength (s) are ____.
589 nm
589.6 nm
Both
None of the above
When the power of eye lens increases, the defect of vision is produced. The defect is known as ____.
shortsightedness
long sightedness
colour blindness
None of the above
A man is suffering from colour blindness for green colour. To remove this defect, he should use goggles of ____.
green colour glasses
red colour glasses
smoky colour glasses
None of the above
In human eye the focusing is done by ____.
to and fro movement of eye lens
to and fro movement of the retina
change in the convexity of the lens surface
change in the refractive index of the eye fluids
A short sighted person can see distinctly only those objects which lie between 10 cm and 100 cm from him. The power of the spectacle lens required to see a distant object is ____.
+ 0.5 D
– 1.0 D
– 10 D
+ 4.0 D
A person can see clearly only upto a distance of 25 cm. He wants to read a book placed at a distance of 50 cm. What kind of lens does he require for his spectacles and what must be its power?
Concave, – 1.0 D
Convex, + 1.5 D
Concave, – 2.0 D
Convex, + 2.0 D
The human eye has a lens which has a ____.
soft portion at its centre
hard surface
varying refractive index
constant refractive index
A man with defective eyes cannot see distinctly object at the distance more than 60 cm from his eyes. The power of the lens to be used is ____.
+ 60 D
– 60 D
– 1.66 D