LIGHT Light is a form of energy that travels by electromagnetic waves.
These waves may be described as the ‘rays’ of light, as they radiate out from a source. They undergo all five of the phenomena of waves: reflection, refraction, diffraction, inter- ference and polarisation.The first of these, reflection, is the focus of this chapter.
Reflection REFLECTION Reflection of light is the way in which light ‘bounces’ off surfaces. This may be diffuse reflection or regular reflection. DIFFUSE REFLECTION
Diffuse reflection is the way in which light is reflected off an object that one would not normally regard as reflective.
REGULAR REFLECTION
Regular reflection is the way in which light reflects off smooth surfaces like mirrors.
This is the type of reflection that is of primary interest to us at Leaving Cert. Physics. TERMS USED TO DESCRIBE REGULAR REFLECTION
An incident ray is the ray of light falling onto the mirror (from an object or a light source).
A normal at the point of incidence is an imaginary line radiating perpendicularly from the mirror at the point where the incident ray strikes the mirror. A reflected ray is the ray of light bouncing off the mirror. An angle of incidence (i) is the angle between the normal and the incident ray. An angle of reflection (r) is the angle between the normal and the reflected ray.
