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