Light is defined as “Electromagnetic Radiation. All light flows in waves in at speed of 300 Million meters second in a vacuum.  In nature a light wave has the shape of a sine (of an angle) along its length and is characterized by a.) amplitude, representing the electrical and magnetic force it can impart and b.)  it’s wavelength or frequency of its oscillations.  See figure 1 below.  The peak of the wave represents its amplitude, “One Wave Cycle” represents its wavelength.

 

Figure 1 The Shape of a Light Wave in Nature (the shape can be modified electronically.

Relationship between Wavelength and Frequency.

In science the speed of light is represented by the letter “c”, frequency by the Greek letter for n being “ν” pronounced “nu”, wavelength by the Greek letter lambda “λ”.  The relationship between the three: ν = c/λ or λ = c/ν

Units of the Properties of Light

c      meters/second or m/s

ν    cycles per second or sec^-1 or wave number (typically for infrared) calculated by 1/(wavelenth        in cm), e.g. wave of 1,000 nm length = 10,000 cm^-1 frequency in wave numbers.  Notice as            the wavelength goes up, the frequency goes down.

λ    meters, cm; micron typically for infrared); millimicron or nanometer, nm (one billionth of a              meter, used for ultraviolet, visible and short-wave infratrd); Angstrom one hundred-millionth        of a meter.

The discussions above are  necessary to understand the depiction of the electromagnetic spectrum below.

Figure 2 The Electomagnetic Spectum.  Units are in meters.

The Duality of Light

Light can act as a particle when hitting a molecule that will accept its energy, raising the molecule’s energy.  This energy can cause an electronic bond to vibrate faster or even break, or cause the molecule to rotate faster or even to move faster.

When a light wave delivers its energy to a molecule it is a called a photon.

A photon is created when a molecule releases its energy to space or to another molecule by spontaneous transition of the molecule’s energy from a higher energy level to a lower level.  These levels are not random, but are quantized, according to the structure and composition of its components.  For example, a hydrogen atom (definition of a molecule of a substance is the lowest part of the substance that can exist as that substance) has energy levels different from all other atoms.

 

This in the realm of quantum physics, initiated by the great scientist Max Planck.  The energy of a e related the energy of a photon to the