In studying physics measurement is the foundation of the subject.
MKS is the system of units based on first three units of base quantities.
Two plane mirrors are used in the periscope to reflect and change the direction of light rays.
Consider an object is placed in front of a plane mirror at a normal or perpendicular distance from it.
Regular Reflection
When a beam of parallel light rays is incident on a smooth and plane surface like a plane mirror, the reflected rays will also be parallel.