# Reflection of Lights Examples with Lenses – Plain, Concave & Convex

Reflection of Lights Examples with Lenses – Plain, Concave & Convex with Definition # What is reflection of light in physics

Light moving in one medium when falls at the surface of another medium, part of light returns back to the same medium. This phenomena of returning back of light in the first medium at the interface of two media is known as reflection of light.

# Laws of Reflection

1. The incident ray, reflected ray and normal to the reflecting surface at the incident point all lie in the same plane.
2. The angle of reflection is equal to the angle of incidence.

# Reflection from plane mirror

1. The image is virtual, laterally inverted.
2. The size of image is equal to that object.
3. The distance of image from the mirror is equal to distance of object from the mirror.
4. If an object moves towards (or away from) a plane mirror with speed v, the images moves towards (or away) with a speed 2v relative to the object.
5. If a plane mirror is rotated by an angle θ, keeping the incident ray fixed, the reflected ray is rotated by an angle 2θ.
6. To see his full image in a plane mirror, a person requires a mirror of at least half of his height.
7. If two planes are inclined to each other at an angle θ, the number of images (n) of a point object formed are determined as follows:

(a) If 360/θ is even integer, then n = 360/θ -1

(b) If 360/θ is odd integer, then

n = 360/θ -1 if the object is symmetrically placed, and

n = 360/θ if the object is symmetrically placed.

(c) If 360/θ is a fraction, then n is equal to integral part.

# Reflection from spherical mirror

Spherical mirror of two types.

1. Concave mirror
2. Convex mirror

# Position & nature of image formed by a spherical mirror

For concave mirror : –

 Object Position Image Position Size of image in comparison to object Image Nature At Infinity At Focus Highly diminished Real, inverted Between infinity and centre of curvature Between focus and centre of curvature Diminished Real, inverted At the centre of curvature At the centre of curvature Of same size Real, inverted Between focus and centre of curvature Between centre of curvature & infinity Enlarged Real, inverted At focus At infinity Highly enlarged Real, inverted Between focus and pole Behind the mirror Enlarged Virtual, erect

For Convex mirror :

 Object Position Image Position Size of image in comparison to object Image Nature At Infinity At Focus Highly diminished Virtual, erect In front of mirror Between pole and focus Diminished Virtual, erect

Note : Image formed by a convex mirror is always virtual, erect and diminished.

# Uses of Concave Mirror

1. As a shaving glass.
2. As a reflector for the head lights of a vehicle, search light.
3. In opthalmoscope to examine eye, ear, nose by doctors.
4. In solar cookers.

# Uses of Convex mirror

1. As a rear mirror in vehicle because it provides the maximum rear field of view and image formed is always erect.
2. In sodium reflector lamp.