Light and Quantized EnergyChapter 5 Section 1

Wave Nature of Light

Visible Light is a type of electromagnetic radiationEM radiation is a form of energy that exhibits

wavelike behavior as it travels through space.

Parts of a Wave

A

B

C

D

Parts of a Wave

A – Crest B – Trough C – Amplitude – height of a wave from the origin D – Wavelength (λ) – crest to crest or trough to

trough Frequency (ν) – the number of waves that pass a

given point per second (1/s, s-1, Hz)

c = λν

c = the speed of light in a vacuum 3.00 x 108 m/s

Longer wavelength = lower frequency Shorter wavelength = higher frequency

Practice Problems What is the wavelength of a wave having a frequency of

3.76 x 1014 Hz?

What is the frequency of a 6.9 x 10-13 m wave?

What is the wavelength of a 2.99 Hz wave?

What is the frequency of a 7.43 x 10-5 m wave?

Electromagnetic Spectrum Includes all forms of electromagnetic radiation with the only

difference in the type of radiation being λ and ν.

Particle Nature of Light

Quantum – the minimum amount of energy that can be gained or lost by an electron

E = hν E = energy

h = Planck’s constant = 6.626 x 10 -34 J·s

ν = frequency (Hz)

Practice Problems

What is the energy of a 7.66 x 1014 Hz wave?

What is the frequency of a wave carrying 8.35 x 10-18 J of energy?

What is the wavelength of a 7.65 x 10-17 J wave?

What is the frequency of a 1.31 x 10-22 J wave? What is the wavelength?

What is the energy of a 3.12 x 1018 Hz wave?

Photoelectric Effect Electrons called photons are

emitted from a metal’s surface when light of a certain frequency shines on the surface

Photons – a massless particle that carries a quantum of energy You find the energy of a photon

the same way you found the energy of a quantum

E = hν

Atomic Emission Spectrum It is the set of frequencies of

the electromagnetic waves emitted by atoms of the element.