Wave Properties of Light

Characterization of Light Light has both a wavelike and particle like nature. Light has both a wavelike and particle like nature. Electromagnetic wave theory: Light is a wave composed of oscillating electric and magnetic fields (electromagnetic wave). Electromagnetic wave theory: Light is a wave composed of oscillating electric and magnetic fields (electromagnetic wave). These waves propagate transversely at right angles to each other. These waves propagate transversely at right angles to each other.

Oscillating Magnetic Field Oscillating Electric Field Characterization of Light

All electromagnetic waves travel at the speed of light (c). All electromagnetic waves travel at the speed of light (c). c = 3.0 x 10 8 m/s Electromagnetic waves vary depending on frequency and wavelength. Electromagnetic waves vary depending on frequency and wavelength. These differences account for the broad range in the electromagnetic spectrum. These differences account for the broad range in the electromagnetic spectrum. Characterization of Light

Electromagnetic Spectrum

The same relationship between frequency, wavelength, and speed that exists in sound waves or objects undergoing SHM also holds true for electromagnetic waves. The same relationship between frequency, wavelength, and speed that exists in sound waves or objects undergoing SHM also holds true for electromagnetic waves. Characterization of Light ν = f λ (classic wave speed equation) c = f λ

Huygen’s Principle Electromagnetic waves travel in wave fronts. Electromagnetic waves travel in wave fronts. Wave fronts are made up of many wavelets, each containing a “point source”. If you make a line tangent to each point source, you have identified a new wave front. Wave fronts are made up of many wavelets, each containing a “point source”. If you make a line tangent to each point source, you have identified a new wave front. Characterization of Light

 Huygens Principle describe waves interacting with matter (diffraction) or waves moving in a straight line.  The perpendicular direction in which the wave front is moving is referred to as a “ray”.

Wave front motion as it moves around an object Characterization of Light

What is the relationship between brightness and the distance from a light source?

Light becomes more spread out and there is less light available per unit area. Light becomes more spread out and there is less light available per unit area. Brightness decreases by the square of the distance from the source. Brightness decreases by the square of the distance from the source. Inverse square relationship ex. There is ¼ as much light falling on a particular spot 2 m away than there is light falling on the same spot that is 1 m away. Characterization of Light