The atmospheric refraction of light causes the twinkling of :
planets only
stars only
planets and stars
stars and satellites
The term "accomodation" as applied to the eye,refers to its ability to :
control the light intensity falling on the retina
erect the inverted image formed on the retina
vary the focal length of the lens
vary the distance between the lens and retina
The red colour of the sun at the time of sunrise and sunset is because :
red colour is least scattered
blue colour is least scattered
red colour is most scattered
blue colour is most scattered
With both eyes open, a person's field of view is about :
90°
150°
180°
360°
The stars appear higher in the sky than they actually are, due to :
diffraction of light
scattering of light
refraction of light
reflection of light
The defect of vision which cannot be corrected by using spectacles is :
myopia
presbyopia
cataract
hypermetropia
We can see the sun before the actual sunrise by about :
5 minutes
2 minutes
2 hours
20 minutes
The animals of prey have :
two eyes at the front
two eyes at the back
two eyes on the sides
one eye at the front and one on the side
The least distance of distinct vision for a young adult with normal vision is about :
25 m
2.5 cm
25 cm
2.5 m
A young man has to hold a book at arm's length to be able to read it clearly.The defect of vision is :
astigmatism
