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Light: It is a type of energy that can be seen by eyes - Coggle Diagram
Light: It is a type of energy that can be seen by eyes
There are two types of objects
luminous
They have a light of their own > firefly
nonluminous
they don't have light of their own >flower
Light travels in a straight line
It speed is 300 000 000m/s
Types of objects
Transparent: Light can clearly pass through for example a glass window
Translucent: Part of the light can pass through for example a stained glass
Opaque: None of the light can pass through for example cardboard
Shadows
They are made when an opaque or translucent blocks light. Shadows are a region of darkness were there is no light.
Shadows are always on the opposite side of the light source. For example if you are standing in front of the sun, the shadow will be behind you on the opposite side of the sun.
If the object moves towards the light source, the shadow will be bigger. The shadow will also have a clearer boundry if the light source is pointing. It is called umbra
If the object moves away from light source, shadow will be smaller and have an unclear boundary. This is called penumbra
Reflection of light
When light strikes a surface it bounces back, Light reflects on smooth shiny or polished surfaces.
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When light falls on a smooth surface, the image will be clear for example a mirror or still water
But when light falls on a rough surface, the image will be scattered and diffused for example a broken mirror
reflection
The light that fall on the object is called incident ray.
The light that bounces back is called reflected ray.
So the angle between the normal and incident ray is called angle of incidence, marked with i
The angle between the normal and reflected ray is called angle of reflection and it is marked with r
Laws of reflection
Angle of reflection and angle of incidence will always be the same.
Incident ray, reflected ray and normal will always be on the same plain
There is a normal and that is used as a refernce. It is at 90 degrees with the plain
Mirror images
They are made when light reflects from a smooth surface and then it goes into our eyes.
< When a mirror image is formed, it will have these properties
letaraly inverted
left side of the object will become right side on the image and right side of the object will become left side on the image.
The distance of the object from the mirror is the same as the distance between mirror & image.
The image will be upright
How eye can see light
When light reflects into our eyes, this is how we can see it
first light fall on the lens of our eye
then it fall on the retina and it is inverted
on retina, there is rod and cone cells and they help form the image
rod and cone cells are conncted to the brain. They brain helps us see the image correctly and it flips the inverted image into its shape
refraction of light
It is when light bends because it changes its median
there is rare median
air
and denser median
water
When light reaches a different median, the light bends. When the light moves from rare to denser median, the light will move towards the normal. When light will move from denser to rare median, then the light will move away the normal.
effects of refraction
apparent depth: things appear to be shallower. for example, if you look at a pool then it will look shallow but when you go in it will be deeper than you thought.
partially emersed object will appear bent. For example putting a pencil in a glass of water then it will appear bent.
dispersion of light
it is when white light splits into 7 colours
The colours are: violet, indigo, blue, green, yellow, orange, red
there is also UV light (ultra violet). The reason they are harmful is because their wavelength is very small and the smaller the wavelength more damage it can cause to the skin and cell in the body.
primary colours are red, yellow and blue. Mixing them can make lots of other colours but these are important, basic colours. red+blue=purple red+yellow=orange blue+yellow=green all of the colours make brown.
Wavelenths
different colours have different wavelengths. It is the distance between 2 waves
red has the longest wave length and violet has the smallest wavelength
