Reflection of Light at Plane Surfaces

When a Real Object is Infront of the Mirror

Consider a real object such as a candle in front of a plane mirror, now observe the image formed, the image is erect, the same size, and off-course virtual in nature and the distance between the candle and the image formed of that candle from the mirror both are equal, so we can say that if the object is real than the image formed will be the virtual, erect and same size as of object.

When an Object moves toward or gets away the Plane Mirror

Now suppose that a person starts moving a candle toward the mirror, then the image of the candle approaches toward mirror at the same speed, same goes for when the candle moves away from the mirror, the speed of the image relative to the object will be given by,

Velocity of object = v_o

velocity of image = v_i  = -v_o

The relative speed of image with respect to object = v_o – v_i = v_o – (-v_o) = 2 v_{o .}

When the Mirror moves toward or gets away from the Object

If a person moves a mirror toward or away from the object with the speed v, then the image will appear moving toward or away from the object with the speed 2v.

Object making certain Angle or Deviation

Through the law of reflection we know that angle of reflection is equal to the angle of reflection, Deviation (∅) is defined as the angle between the direction of the incidence ray and the emergent ray, Suppose that if the ray of the light incident over the surface with angle i, then the deviation is given as:

Angle of deviation, ∅ = 180 – ( i + r) = 180 – 2i ,

the maximum deviation is occur when angle of incidence is 0°, 

∅ _max = 180 – 2 × 0 = 180°

Mirror is Rotated through a certain Angle

Consider the object placed at a fixed position from the mirror, if a plane mirror is rotated through an angle θ, then the reflected ray also rotates through an angle of twice of a rotating plane mirror, i.e. (2θ). But the size of the image remains unchanged.

Reflection of Light at Plane Surfaces occurs whenever a ray of light strikes or falls over a smooth or polished surface and gets strikes back. In simple words, the ray of light approaching or striking any surface results in the reflection of the light. the ray of light which approaches the reflecting surface or incident over it is known as an incident ray and the ray which reflects back after the strike is known as a reflected ray. If a perpendicular is to be drawn between the incident and reflected rays on the reflecting surface, it is known as a Normal. Let’s Learn more about the Reflection of Light on Plane Surfaces and the Reflection on a Plane Mirror in this article!