Which type of the image is formed by the plane mirror?
a) real
b) virtual
c) both a and b
d) none of them
Which of the following is an optical device?
a) thermometer
b) periscope
c) sphygmomanometer
d) none of these
A periscope is
an optical device that uses.…… to reflect images through a tube?
a) concave lenses
b) mirrors
c) convex lenses
d) all of these
What is the angle between two mirrors in the simple periscope?
a) 30
b) 45
c) 60
d) 90
How many times the light rays coming from the object behind obstacle are reflected in periscope?
a) two
b) three
c) four
d) five
Explanation:A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position.In its simplest form, it consists of an outer case with mirrors at each end set parallel to each other at a 45° angle. This form of periscope, with the addition of two simple lenses, served for observation purposes in the trenches during World War I. Military personnel also use periscopes in some gun turrets and in armored vehicles.
How many plane mirrors are used in the simple periscope?
a) two
b) three
c) four
d) five
