Controls the amount of light entering the eye?
(A) Iris
(B) pupil
(C) lens
(D) side muscles
If the reflection formed in the mirror is always perpendicular to the object in shape, is the mirror?
(A) concave
(B) convex
(C) level
(D) None of these
When the object moves with speed u towards (or away) from the plane mirror then image also moves toward (or away) with speed u. But relative speed of image w.r.t. object is 2u.
Which of the following substances cannot be used for lenses?
(A) Water
(B) Soil
(C) Plastic
(D) glass
What is the orbital velocity of the geostationary satellite?
(A) 3.08 km /s
(B) 6.66 km /s
(C) 4.15 km /s
(D) 2.78 km /s
Alum is used as:
(A) a disinfectant
(B) a purifier for water
(C) an analgesic
(D) a fertilizer
Seawater can be purified by the process of -
(A) filtration
(B) fractional distillation
(C) distillation
(D) evaporation
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