The Nature of Light 

Concept #1: The electromagnetic spectrum represents the full range of frequencies and wavelengths that spread across forms of electromagnetic radiation. 

Concept #2: By examining the electromagnetic spectrum connections between energy, frequency, wavelength and amplitude can be made. 

Properties of Light

Concept #3: Using the speed of light constant allows for the correlation between frequency and wavelength. 

Example #1:

Calculate the wavelength (in nm) of the red light emitted by a neon sign with a frequency of 4.16 ×108 MHz.


Example #2:

What is the energy, in joules, of a mole of photons associated with visible light of wavelength 493 nm?


Properties of Light Calculations 

Example #3:

A laser pulse produces 1.242 kJ of energy. It was experimentally determined that the pulse contains 3.50 x 1022 photons. Determine the wavelength of light (in meters) emitted by one photon.


Example #4:

How much total energy (in μJ/mol) would it take to remove the electrons from a mole of hydrogen atoms?

The ionization energy for a hydrogen atom is 2.178 x 10-18 J.



Practice: A low-pressure mercury-vapor lamp has a characteristic emission line at 253 nm. Knowing that this lamp is putting out 11.8 watts of light energy, how many mercury atoms are emitted per second during operation?