List of top Science Questions on Optics asked in UP Board X

The blue colour of the sky is due to the
The unit of power of a lens is
What is short-sightedness (myopia)? Explain with a ray diagram. This defect is corrected by which type of lens?
What are the defects of vision? Write down the names of the lenses used for the correction of vision defect of three persons P, Q, and R if —
(i) \( P \) can see only near objects clearly but cannot see far objects.
(ii) \( Q \) can see only far objects clearly but cannot see near objects.
(iii) \( R \) can neither see far objects nor near objects clearly.
The speeds of light in water and glass are respectively \( 2.25 \times 10^8 \, \text{m/s} \) and \( 2.0 \times 10^8 \, \text{m/s} \). Calculate the following refractive indices:
(i) The glass relative to water.
(ii) The glass relative to air.
The power of a lens is +2 dioptre. What will be its focal length in cm?
In a spherical mirror the distance between its centre of curvature and pole is 20 cm. What is the distance of focus from the pole of the mirror?
Due to which phenomenon of light does the sky appear blue?
From which lens the image of object formed is virtual, erect and smaller than the object?
Write down two uses each of convex mirror and convex lens.
Draw a ray diagram of the image of an object formed by a concave lens.
Which of the following lenses should be used to read small letters?
The cause of twinkling of stars is:
The image by a convex mirror of an object placed at infinity is:
The colour having the largest angle of deviation on passing white light through a prism will be:
An object of 3 cm height is placed at a distance of 8 cm from a concave mirror which produces a virtual image of 4.5 cm height. Find the position of the image and focal length of the mirror.
Explain why the colour of the clear sky appears blue.
Which type of mirror is used as a rear-view mirror in cars? Why do we prefer it?
The magnification produced by a convex mirror is always
The focal length of a converging lens is 20 cm. The power of this lens will be
When a beam of white light falls on the surface of a triangular glass prism it splits, after emerging out from the prism into various colours with different deviations. The colour which has minimum deviation is
A convex lens of focal length 10 cm forms a real image of the same size as the object. The distance between the object and its image will be:
Atmospheric ozone layer protects the Earth from:
A convex mirror of radius of curvature 4 meters is attached to a motor-bike to watch any other vehicle coming from behind. Calculate the location and position of the image of a vehicle which is 8 meters behind the bike at the time, as seen in the mirror.
The speed of light is maximum in: