Light, Reflection and Refraction

Light:

-A form of energy
-Can be obtained from a luminous source or reflected off non-luminous objects
-travels in a straight line

Reflection

The Laws of Reflection:

1. The incident ray, reflected ray and the normal lie on the same plane
2.The angle of incidence is equal to the angle of reflection.

Characteristics of plane mirror image:

-same size as object
-laterally inverted
-virtual - cannot be captured on a screen
-upright
-distance between image and mirror is the same as the distance between object and mirror


Refraction

Definition:

When light rays strike an optical medium, the light that is transmitted through the medium bends due to the difference of optical density between air and the block of plastic/glass. This light-bending effect is called refraction.


From this diagram, we can see that as the light ray passes through glass, which is an optically denser medium, from air, thus it will bend more and when it travels from glass to air, it will bend more inwards.


TOTAL INTERNAL REFLECTION

The critical angle is defined as the angle of incidence in the optically denser medium for which the angle of refraction in the less dense medium is 90 degrees.

incident angles greater than the critical angle there will be total internal reflection.

When does total internal reflection occur?

Total internal reflection takes place only when a ray of light travels from an optically denser to a less dense medium, and the angle of incidence in the optically denser medium is greater than the critical angle.