Two convex lenses with power 2 dioptre are kept in contact with each other. The focal length of the combined lens system is
Which one of the following statements about the refractive index of a material medium with respect to air is correct?
Which one of the following is the natural phenomenon based on which a simple periscope works?
A myopic person has a power of -1.25 Dioptre. What is the focal length and nature of his lens?
Which one of the following processes explains the splitting of a beam of white light into its constituent colours?
If the speed of light in air is 3 x 108 m/s, the speed of light in glass (with refractive index 1.5) would be
While looking at the image formed by a convex lens (one half of the lens is covered with black paper), which one of the following will happen to the image?
A person standing in front of a plane mirror approaches the mirror by 40 cm. The new distance between the person and his image in the plane mirror is
An optical illusion which occurs mainly in deserts during hot summer is based on the principle of
A rainbow is produced due to which one of the following phenomena?
Concave mirror is used in headlights of vehicles, because it
The mirrors used as rear-view mirrors in vehicles are
How long does light take to reach the Earth from the Sun?
The focal length of the eye lens increases when eye muscles
When light rays enter the eye, most of the refraction occurs at the
Which of the following phenomena contributes significantly to the reddish appearance of the sun at sunrise or sunset?
The clear sky appears blue because
Which of the following phenomena of light are involved in the formation of a rainbow?
A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power
Rays from Sun converge at a point 15 cm in front of a concave mirror. Where should an object be placed so that size of its image is equal to the size of the object?
Magnification produced by a rear view mirror fitted in vehicles
A 10 mm long awl pin is placed vertically in front of a concave mirror. A 5 mm long image of the awl pin is formed at 30 cm in front of the mirror. The focal length of this mirror is
Which of the following can make a parallel beam of light when light from a point source is incident on it?
Two mirrors A and B are placed at right angles to each other as shown in Figure.
A ray of light incident on mirror A at an angle of 25° falls on mirror B after reflection. The angle of reflection for the ray reflected from mirror B would be
Part of the eye which controls the light entering is called
If an object is placed at a distance of 0.5 m in front of a plane mirror, the distance between the object and the image formed by the mirror will be
Which of the following can be used to form a real image?