The Electromagnetic Spectrum Part 1 Chapter 4 The Electromagnetic Spectrum Part 1

Visible Light Part of the Electromagnetic Spectrum

All types of electromagnetic energy move in waves. Light and sound move by waves. Light moves at 3 x 108 m/s Sound moves at 340 m/s 1 mile = 1609 m

All types of electromagnetic energy move in waves. Light moves at 3 x 108 m/s Sound moves at 340 m/s Is sound a form of electromagnetic radiation?

Electromagnetic Waves Properties of waves include speed, frequency and wavelength All electromagnetic waves including light travel at a speed of 3 x 108 m/s.

Wavelength () Measured in units of length: m, nm, A º

Frequency () Measured in cycles/second = hertz (Hz)

Visible Light

Why do we want to understand electromagnetic radiation (light)? Well, for one thing, it may someday allow us to become invisible.

Electromagnetic Radiation For all waves  •  = c c = the speed of light = 3.00 x 108 m/s

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the frequency of this light?

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the frequency of this light? 665 nm = 665 x 10-9 m

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the frequency of this light? 665 nm = 665 x 10-9 m c =  • 

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the frequency of this light? 665 nm = 665 x 10-9 m c =  •   = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the frequency of this light? 665 nm = 665 x 10-9 m c =  •   = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m  = 4.511278 x 1014/s or Hz

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the frequency of this light? 665 nm = 665 x 10-9 m c =  •   = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m  = 4.511278 x 1014/s or Hz  = 4.51 x 1014/s or Hz

An x-ray has a frequency of 7.25 x 1020 Hz. What is the wavelength?

An x-ray has a frequency of 7.25 x 1020 Hz. What is the wavelength? 7.25 x 1020 Hz = 7.25 x 1020/s

An x-ray has a frequency of 7.25 x 1020 Hz. What is the wavelength? 7.25 x 1020 Hz = 7.25 x 1020/s c =  • 

An x-ray has a frequency of 7.25 x 1020 Hz. What is the wavelength? 7.25 x 1020 Hz = 7.25 x 1020/s c =  •   = c ÷  = 3.00 x 108 m/s ÷ 7.25 x 1020/s

An x-ray has a frequency of 7.25 x 1020 Hz. What is the wavelength? 7.25 x 1020 Hz = 7.25 x 1020/s c =  •   = c ÷  = 3.00 x 108 m/s ÷ 7.25 x 1020/s  = 4.137931 x 10-13 m

An x-ray has a frequency of 7.25 x 1020 Hz. What is the wavelength? 7.25 x 1020 Hz = 7.25 x 1020/s c =  •   = c ÷  = 3.00 x 108 m/s ÷ 7.25 x 1020/s  = 4.137931 x 10-13 m  = 4.14 x 10-13 m

Energy of Electromagnetic Radiation For all waves: E = h •  h = 6.63 x 10-34 J • s or J/Hz

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the energy of this light?

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the energy of this light? 665 nm = 665 x 10-9 m c =  •   = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m  = 4.511278 x 1014/s or Hz  = 4.51 x 1014/s or Hz

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the energy of this light? 665 nm = 665 x 10-9 m c =  •   = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m  = 4.511278 x 1014/s or Hz  = 4.51 x 1014/s or Hz E = h •  = (6.63 x 10-34 J • s)(4.51 x 1014/s)

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the energy of this light? 665 nm = 665 x 10-9 m c =  •   = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m  = 4.511278 x 1014/s or Hz  = 4.51 x 1014/s or Hz E = h •  = (6.63 x 10-34 J • s)(4.51 x 1014/s) E = 2.99013 x 10-19 J

A photon of red light has a wavelength of 665 nm A photon of red light has a wavelength of 665 nm. What is the energy of this light? 665 nm = 665 x 10-9 m c =  •   = c ÷  = 3.00 x 108 m/s ÷ 665 x 10-9 m  = 4.511278 x 1014/s or Hz  = 4.51 x 1014/s or Hz E = h •  = (6.63 x 10-34 J • s)(4.51 x 1014/s) E = 2.99013 x 10-19 J = 2.99 x 10-19 J

An x-ray has a frequency of 7.25 x 1020 Hz. What is its energy?

An x-ray has a frequency of 7.25 x 1020 Hz. What is it’s energy? E = h •  = (6.63 x 10-34 J/Hz)(7.25 x 1020Hz)

An x-ray has a frequency of 7.25 x 1020 Hz. What is it’s energy? E = h •  = (6.63 x 10-34 J/Hz)(7.25 x 1020Hz) E = 4.80675 x 10-13 J

An x-ray has a frequency of 7.25 x 1020 Hz. What is it’s energy? E = h •  = (6.63 x 10-34 J/Hz)(7.25 x 1020Hz) E = 4.80675 x 10-13 J E = 4.81 x 10-13 J

wavelength, frequency and energy Red Light  = 665 x 10-9 m  = 4.51 x 1014 Hz E = 2.99 x 10-19 J  = 4.14 x 10-13 m  = 7.25 x 1020 Hz E = 4.81 x 10-13 J X-ray

Wavelength, frequency and energy Wavelength and frequency have an inverse relationship. Energy and frequency have a direct relationship. Electromagnetic radiation with a shorter wavelength will have a higher frequency and higher energy. Electromagnetic radiation with a longer wavelength will have a lower frequency and lower energy.