Friday, 1 May 2015

FORM 4: 5.1 UNDERSTANDING REFLECTION OF LIGHT

PLANE MIRROR
We are able to see because light from an object can move through space and reach our eyes.

THE LAWS OF REFLECTION
1.       The incident ray, the reflected ray and the normal all lie in the same plane.
2.       The angle of incidence, i is equal to the angle of reflection, r.

RAY DIAGRAM OF THE IMAGE FORMED BY A PLANE MIRROR
THE CHARACTERISTICS OF THE IMAGE FORMED BY A PLANE MIRROR:
1.       laterally inverted
2.       same size as the object
3.       virtual
4.       as far behind the mirror as the object as the object is in front of it

CURVED MIRROR
1.       The centre of curvature, C of curved mirror is the centre of sphere of the mirror.
2.       The radius of curvature, R is the distance between the centre of curvature, C and the surface of the mirror.
3.       The principal axis is the connecting line from the centre of curvature to point P.

4.       The focal point, F is the point on principal axis where parallel rays that strike the surface of a convex mirror will be reflected and the diverging rays appear to come from a point inside the concave mirror.
5.       The focal length, f is the distance between the centre of curvature, C and the focal point, F. (CF = FP)

RAY DIAGRAM OF THE IMAGE FORMED BY A CONCAVE MIRROR

RAY DIAGRAM OF THE IMAGE FORMED BY A CONVEX MIRROR

APPLICATIONS OF PLANE MIRROR
MIRROR IN A METER
The correct reading can only be taken when the image of pointer is exactly under the pointer.

SIMPLE PERISCOPE
§   A simple periscope consists of two plane mirrors inclined at an angle of 45o.
§   A periscope can be used to see over the top of high obstacles such as a wall.
§   It is also used inside a submarine to observe the surrounding above water surface.

OHP (OVERHEAD PROJECTOR)
OHP uses plane mirror to reflect the image to the screen.

APPLICATIONS OF CONCAVE MIRROR
TORCHES & CAR HEADLAMP
A small lamp is placed at the focus point of the mirror to produce parallel rays.

APPLICATIONS OF CONVEX MIRROR
SECURITY MIRROR
A security mirror made from a convex mirror helps to widen field of vision for security purposes.

1 comment:

  1. Very nice job!
    A couple of questions on the OHP scheme: What is the purpose of using a "focus lense"? Why do the lines meet/cross each other after the "plane mirror"?
    Thank you!

    Constantine
    Athens, Greece

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