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Answers
Answer:
- Luminous objects are Objects that do not give out or emit light of their own.Luminous objects can cause the sensation of light.Luminous objects are visible as they emit light of their own.Examples of luminous objects include: Sun, Stars, Candle, Oil lamp, Torch, Electrical bulb, Glowing insects, tube light etc.
Non-luminous objects are objects that do not give out or emit light of their own. Non-luminous objects do not cause the sensation of light.Non-luminous objects are visible because of luminous objects.Examples of non-luminous objects/bodies include: Earth, Moon, Piece of cloth, Coal, Table, Chair, Eraser, Pen, Pencil etc.
2. Reflection is when light bounces off an object. If the surface is smooth and shiny, like glass, water or polished metal, the light will reflect at the same angle as it hit the surface. Examples : Reflection by a plane mirror , Reflection by a spherical mirror
3. Laws of reflection
(i) The incident ray, the reflected ray and the normal at the point of incidence, lie in the same plane.
(ii) The angle of incidence and angle of reflection are equal i.e. ∠i = ∠r.
Verification :
Take a wooden drawing board and fix a white sheet of paper on it. In the middle of paper draw a straight line KK\ Mark a point B on it. Draw a perpendicular BN. Place a mirror XX’ on line KK’ such that polished side of mirror is along the line. Hold-the mirror in the mirror holder.Fix two steel pins P and Q on the straight line AB at least 10 cm apart. Look for the images of the pins P and Q and fix two pins P Q’ such that P’, Q’ and images of P and Q are all in the same straight line. Remove the pins and draw small circles around the pin pricks.
Remove the mirror also. Join P’Q’ and produce the straight line to meet at B.
Measure ∠ABN = i and ∠CBN = r.
It is found that ∠i = ∠r. This proves that Angle of Incidence is equal to Angle of Reflection.
As the incident ray, the reflected ray and the normal lie in the plane of paper, therefore, they lie in the same plane.
4. Point of incidence: The point on the surface where the incident ray strikes the surface is called the point of incidence.
Incident ray - A ray of light falling on the surface separating two mediums is the incident ray.
Answer:
1. Luminous objects:The object which emit light energy by themselves are called luminous objects.Examples - sun, candle, electric bulb.
Non-luminous objects:The objects which does not emit light energy by themselves are called non-luminous objects.Examples - moon, chair, plants
2. A phenomenon of returning light from the surface of an object when the light is incident on it is called reflection of light. Examples: Reflection by a plane mirror.
3.Laws of reflection are: (i) The incident ray, the reflected ray and the normal ray at the point of incidence, lie in the same plane. (ii) The angle of incidence is equal to the angle of reflection.
4.Plane of incidence : A plane containing an incident line (as a ray of light) and the normal to a surface (as of a mirror) at the point of incidence.
Incident ray: The Ray of light which falls on the surface of the mirror or strikes a reflecting surface is called the incident ray.
Hope it helps you^_^