Light and Quantized Energy Light and Quantized Energy Essential Question: What are the quantitative and qualitative properties across the range of the electromagnetic spectrum? How would you use the formula c= v and E=hf in wave calculations?

Characteristics of Waves Wavelength ( λ ) – shortest distance between 2 equivalent points on a continuous waves (from crest to crest or from trough to trough) Units of wavelength: Usually in meters, centimeters or nanometers

Comparing Wavelengths Wavelength crest trough Wavelength long wavelength short wavelength 1.Which wave has a longer wavelength? 2.Which wave has the shorter wavelength?

Characteristics of Waves Frequency ( v ) – number of waves that pass a given point per second Units of frequency: waves per second 1 / s = s -1 = Hertz

So which type of wave has a higher frequency……one with a long wave length or one with a short wavelength Wave A Wave B Wave C

Another way to look at Frequency low frequency high frequency = short wavelength = long wavelength These 2 waves are traveling at = speeds… These 2 waves are traveling at = speeds… more crests cross the ‘finish line’ in a matter of one min.? which wave will have

Characteristics of a Wave Amplitude – wave’s height from the origin of the wave to the crest or from the origin to the trough origin

Parts of a wave wavelength peak trough amplitude

Vocab & Symbols Speed of light (c) – constant number, 3.00 x 10 8 m/s Wavelength ( λ ) – shortest distance between 2 equivalent points on a continuous waves; measured in m Frequency ( v ) – number of waves that pass a given point per second; measured in Hz Energy (E) – energy of the photon as it travel; measured in Joules, J Planck’s Constant (h) – constant number, x J. s

Wave Calculations All electromagnetic waves travel at the speed of light in a vacuum Speed of light (c) = 3.00 x 10 8 m/s Speed of light is equal to product of wavelength and frequency c = λ v Rearrange to solve for wavelength or frequency. Remember speed of light (c) is always the same number

Isolating Algebraically To solve for wavelength: To solve for wavelength: λ = c / v To solve for frequency: To solve for frequency: v = c / λ Magic Triangle

Wave Calculations Practice Calculate the υ of a wave that has a wavelength of 5.00 x 10-6 m. νc= λ What is the λ of radiation with a frequency of 1.50 x Hz? What is the λ of radiation with a frequency of 1.50 x Hz?cλ = ν

Energy Calculations All energy is a multiple of Planck’s Constant, a quantum of action in quantum mechanics h = x J. s Energy of a photon is calculated by the multiple of Planck’s constant by frequency E = h v Rearrange to solve for energy or frequency. Remember Planck’s constant (h) is always the same number

Isolating Algebraically To solve for energy: To solve for energy: E = h x v To solve for frequency: To solve for frequency: v = E / h Magic Triangle

Energy Calculations Practice Calculate the E of a wave that has a frequency of 7.66 x 1014 Hz.E h h x= What is the of radiation with 8.35 x J of energy? What is the υ of radiation with 8.35 x J of energy? E= h ν ν

Using BOTH Formulas What is the energy of a 9.3 x m wave? What is the wavelength of a x J wave?