Understanding the Reflection of Light: Law of Reflection of Light

1. The reflection of light can be studied by using light ray(s) and a plane of mirror which is placed on a piece of white paper.

image from: http://www.hsphys.com/pmirrb.jpg

2. When the ray of light is incident onto the surface of a plane mirror, the light ray does not pass through the mirror but is reflected back by the plane mirror.

3. The phenomena of ths experiment shows the phenomena of reflected light.

The Law of Reflection of Light States that:

1. The incident Ray, the reflected ray and the normal all lie in the same plane.

2. The angle of incidence is equal to the angle of reflection.


Image courtesy:
http://www.curriki.org/xwiki/bin/download/Coll_Athabasca/Unit3-Lesson2TheMovementofLight/reflection.jpg

More information at:

www.hsphys.com/ light_and_optics.html

Characteristics of Image that is formed on a plane mirror

1) It is upright
2) It is virtual
3) The distance form the object to the mirror is the same as the distance from the image to the mirror.
4) It is the same size as the object
5) It is laterally inverted

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Specific Heat Capacity

Specific Heat Capacity

1. Specific heat capacity, c, of a body is the heat that is needed to increase the heat of a unit of mass or the substance by 1°C or 1K.
2. The unit of specific heat capacity is Jkg-1°C-1.
3. For example, the specific heat capacity of water is 4200 Jkg-1°C-1 . This means that 4200J of heat is needed to increase the temperature of 1 Kg of water by 1°C.
4. Therefore, when a body of a mass m and specific heat capacity, c, absorbs a quantity of Heat, H, then its heat will increase by θ.
5. Therefore H = mc θ.
6. On the contrary, when the heat of a body falls by θ, the quantity of heat that disappears (lost) is also H = mc θ.
7. The specific heat capacity is dependent upon the type of substances. Different substances have different specific heat capacity.
8. By knowing the specific heat capacity, we can determine the mass and also the change of temperature of a body if we know the amount of heat that is transferred.
9. Total heat transferred H = mc θ.
10. Generally, liquid has more specific heat capacity than solids. This means that liquids need more heat energy than solids for the same rise in temperature.