You are not a member of this wiki.
Pages and Files
Assessment of Students' Contributions.
1.1 Sensory Organs and Their Functions
1.2 The Sense of Touch
1.3 The Sense of Smell
1.4 The Sense of Taste
1.5 The Sense of Hearing
1.6 The Sense of Sight
1.7 Light and Sight
1.8 Sound and Hearing
1.9 Stimuli and Responses in Plants
2.1 The Classes of Food
2.2 Balanced Diet
2.3 Digestive System in Man
2.4 The Process of Absorption of Digested Food
2.5 The Reabsorption of Water and Defection
2.6 The Habits of Healthy Living
1.7 Light and Sight
Topics for discussion:
1.Properties of light
Speed of light
2. Defects of vision
3. Limitations of sight
The blind spot
4. Stereoscopic and monocular vision
5. Devices used to overcome the limitations of sight
Ultrasound scanning device (Ultrasonography)
1.7 Light and Sight
Characteristics of light
1. Light travels in a straight line.
a. This characteristics of light leads to occurrences such as shadow formation, eclipse of the Sun and eclipse of the Moon.
b. An object which allows light to pass through it, is called a transparent object. Examples : A prism and a clear glass.
c. An object which does not allow light to pass through it, is called an opaque object. Example : Wood and paper.
d. Shadows are formed when light is blocked by opaque objects.
e. The formation of a shadow depends on the size and angle of the source of the light.
is the dark shadowy area.
is the shadowy area that is not clear.
that occur due to the characteristic of light travelling in a straight line are :
A lunar eclipse that occurs when the Earth is situated between the Moon and the Sun. The shadow of the Earth falls on the surface of the Moon to appear invisible.
A solar eclipse that occurs when the Moon is situated between the Earth and the Sun. The shadow of the Moon falls on the surface of the Earth and causes that part of the Earth to experience darkness.
Reflection and Refraction of Light
Light changes in direction by reflection and refraction. These properties occur during our daily life.
E.g : Refraction of Light : A stick to appear bent in water and a swimming pool to appear shallower.
Reflection of light : Diamonds sparkle because they reflect light falling on them.
~kah long~ =)
Reflection of Light
1. Light which falls on an object is
by the object onto our eyes. The reflected light allows us to see the object.
2. An opaque object does not allow light to pass through it. Some of the light will be
and some of it will be reflected.
3. Reflection of light depends on:
The colour of the object
A bright object reflects more light than a dark object.
The condition of the object's surface
Flat and smooth surfaces reflect more light than rough and uneven surfaces.
4. The characteristics of the image on a plane mirror.
(cannot) be traced on the screen
as the object
The distance of the object from the plane mirror is the
as the distance of the image from the plane mirror.
Properties of Light
2. Light can be
bending of light ray when it enters a medium of different density
- e.g. Medium to higher density : the speed increases
Lower to higher density : the speed decreases
3. Light can be reflected
4. Light acts as an
Thomas Young's Wave Theory
5. Light travels 300 000 000 000 000 m/s in vacuum
Diagram : speed of light from the Earth to the Moon
How A Prism Works
- When light is travels from a medium of lower density to a medium of higher density the speed of light decreases.
- Reflection of light occurs when light
off the surface of an object.
- Light can travel through difference medium such as air, water, glass and plastic.
- Speed changes when light travels from one medium to another.
- The bending of light ray when it enters a medium of different density is known as refraction of light.
Light and Sight
1. Light travel
- In a straight line
- 3x10 power of 8 ms-1
- Through vacuum (sound cannot travel through vacuum
2. Light can travel
- Through transparent media (air, water, glass, plastic and etc.)
- From one medium to another but the speed changes
Reflection and Refraction
- Reflection of light occurs when light bounces off the surface of an object.
- The bending of a light ray when it enters a medium of different density is known as the refraction of light.
- When light travels from a medium of lower density to a medium of a higher density, the speed of light decreases.
- When light travels from a medium of higher density to a medium of a lower density, the speed of light increases.
Law of Reflection
Law of reflection states that when a ray of light reflects of a surface, the angle of incidence is equal to the angle of reflection and the incident ray is on the same place.
Short-sightedness (Myopia) and Long-sightedness (Hyperopia/Hypermetropia)
1. Short- sightedness
- Can see near objects
- Cannot focus on distance object
- Distance object is focus in front of the retina
- Eyeball is too long
- Use a concave lens
- Can see far objects
- Cannot focus on near objects
- Near objects is focus at the back of the retina
- Eyeball is too short
- Use a convex lens
- Irregular surface of the cornea
- See some parts of an object more clearly than other parts
- See lines in one direction clearer than other lines in other direction
- May see world as a distorted images
- Use a cylindrical lens
- Go through surgery
help on how to format text
Turn off "Getting Started"