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Tag: LIGHT
Light | Study
LIGHT | Study
Light | Study
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Light | Speed Notes
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Light: It is the natural agent that stimulates sight and makes things visible.
Light travels along straight line.
Any polished or a shining surface acts as a mirror.
An image which can be obtained on a screen is called a real image. (Scroll down to continue …).
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It is formed by light rays that actually pass through the screen.
An image which cannot be obtained on a screen is called a virtual image.
It is formed by light rays that seem to pass through the screen.
The image formed by a plane mirror is erect.
It is virtual and is of the same size as the object.
The image is at the same distance behind the mirror as the object is in front of it.
In an image formed by a mirror, the left side of the object is seen on the right side in the image, and right side of the object appears to be on the left side in the image.
A concave mirror can form a real and inverted image.
When the object is placed very close to the mirror, the image formed is virtual, erect and magnified.
A Convex mirror is the mirror that curves out; the reflecting surface is convex.
Image formed is virtual, upright and diminished. Image formed by a convex mirror is erect, virtual and smaller in size than the object.
A Concave lens is the lens that is thinner at the center than at the edges.
It is a diverging lens.
Image formed is virtual, erect and diminished.
A convex lens can form real and inverted image.
When the object is placed very close to the lens, the image formed is virtual, erect and magnified.
When used to see objects magnified, the convex lens is called a magnifying glass.
White light is composed of seven colors.
Properties of Light:
1. Rectilinear Propagation of Light: It is the property of light by which it travels in a straight line in any direction.
The direction of path in which light make a ray.
2. Reflection of Light: It is the bouncing back of light after striking the surface of an object.
Shiny smooth surfaces reflect almost all the light.
3. Dispersion: It is the phenomenon of splitting of white light into its seven colors. White
light is mixture of: Violet, Indigo, Blue, Green, Yellow, Orange and Red (VIBGYOR) colors.
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LIGHT | Study
Pre-Requisires
Test & Enrich
Speed Notes
Notes For Quick Recap
Light
Light is the natural agent that stimulates sight and makes things visible. Light is reflected from all surfaces. It is a form of energy.
Reflection of Light: Bouncing back of light after striking any surface such as a rough surface, Smooth surfce, shiny surface or polished surface, into the same medium, is called reflection of light. (Scroll down to continue …)
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luminous objects: Objects that give out light on their own are called luminous objects.
Examples: Flame, Sun, Glowing bulb
Non-luminous objects: Objects that do not give out light on their own are called non-luminous objects.
Examples: Rocks, Plasic Toys, Walls of room.
The Non – Luuminous objects, reflect light that falls on them.
When the reflected light enters into our eyes from the objects we could see them.
Types of Reflection:
(i) Regular Reflection: When a beam of parallel light rays is incident on a smooth and plane surface, the reflected rays will also be parallel. This type of reflection is called Regular Reflection.The reflection from a plane mirror is an example of regular reflection.
(ii) Diffused or Irregular Reflection: When a parallel beam of light is incident upon a rough or uneven surface, it is reflected in many directions due to presence of irregularities on that.
multiple reflections: If a reflected light ray is reflected again on being incident on another surface, it is termed as multiple reflections.
Multiple reflections are used in periscope, kaleidoscope etc.
Periscopes are used in submarines, war tanks and by soldiers in bunkers to see objects.
In a kaleidoscope, beautiful patterns are formed due to multiple reflections.
Laws of reflection of light:
(i) The angle of incidence is equal to the angle of reflection.
(ii) Incident ray, reflected ray and the normal drawn at the point of incidence to the reflecting surface, lie in the same plane.
Lateral inversion: Lateral inversion is the effect produced by a plane mirror in reversing images from left to right.
Example: Our left hand will appear as right and vice versa.
Characteristics of the image formed by a plane mirror
Size the image formed by a plane mirror is equal to the siz of the object.
The image formed by the plane mirror is left-right inverted.
The image formed by the plane mirror erect and virtual formed behind the mirror.
Since the distance of the object in front of the mirror two mirrors inclined to each other give multiple images.
Sunlight: Sunlight, called white light, consists of seven colours.
dispersion: Splitting of light into its constituent colours is known as dispersion.
Human Eye:
A normal eye can see nearby and distant objects clearly.
Visually challenged persons can read and write using Braille system.
Visually challenged persons develop their other senses more sharply to improve their interaction with their environment.
Parts of Human Eye:
(i) Cornea: Transparent bulge on the front surface of the eyeball which protects the eye andhelps in refraction of light.(ii) Iris: Coloured diaphragm behind the cornea which controls the amount of light
entering the eye.(iii) Pupil: Dark hole in the middle of iris through which light enters the eye. (iv) Eye lens: Transparent, crystalline structure behind pupil and iris. (v) Ciliary muscles: Hole the eye lens in position and control the focal length of the eye lens.
(vi) Retina: Surface of the rear part of the eyeball where the light entering the eye is focused.
(vii) Rods and Cones: Rod cells respond to the brightness of light while cone cells.
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