Post on 21-Jan-2016
Waves & EnergyH Ch 5&6
Waves Vibrating disturbance by which energy is transmitted
Am
plitu
de
Am
plit
ud
e
(Wavelength)
(Wavelength)u = λν
Calculate the wavelength () of yellow light if its frequency () is 5.10 x 1014 Hz.
Example 1
= c ÷ = 3 x 108 m/s ÷ 5.10 x 1014 Hz = 5.88 x 10-7 m
What is the frequency () of radiation with a wavelength () of 5.00 x 10-8 m? What region of the electromagnetic spectrum is this radiation?
Example 2
= c ÷ = 3 x 108 m/s ÷ 5.00 x 10-8 m = 6.00 x 1015 1/sultraviolet region (just barely)to find out look at a chart
Electromagnetic Radiation
c = λν
c = 3.0×108
When solids are heated, they emit electromagnetic radiation over a wide range of wavelengths
Atoms and molecules could emit (or absorb) energy in discrete quantities, like small packages or bundles
Quantum Theory
E = h x nPlanck’s constant (h)h = 6.63 x 10-34 J•s
E = hc / λBecause ν = c/λ
How much energy does a wave have with a frequency of 2.0 x 108 Hz? ( h = 6.626 x 10-34 J.s)
Example 1
E =hE = (6.626 x 10-34 Joule s)(2.0 x 108 s-1)E = 1.3 x 10-25 Joule
Phenomenon in which electrons are ejected from the surface of certain metals exposed to light
Photon is a “particle” of light
Photoelectric Effect
hn
KE e-
E = h x n
Particle-Wave Duality
Possessing both particle like and wave like properties
Not unique to light, but is also characteristic of all matter including e−
Bohr’s Theory
• e- can only have specific (quantized) energy values
• light is emitted as e- moves from one energy level to a lower energy level
Spectroscope Instrument used to measure properties of light
over a specific portion of the em spectrum
Emission Spectra
Line Emission Spectrum of Hydrogen Atoms
Energize the
sample
16
Flame Test
Neon Signs