lOMoARcPSD|64109549
Module II
lunes, 13 de enero de 2025
12:11 p. m.
The Nature of Light - Light interacts with matter.
Waves an oscillation or periodic movement that can transport energy from one point to another.
Electromagnetic waves consist of both electric and magnetic field, oscillating perpendicular to one
another. Both travel in the same direction.
Wavelength (λ - lambda) - distance between two peaks or troughs, measured in meters.
Can be measured from the top (peak) or bottom (trough) of the wave.
Frequency (ν - nu) - number of wave cycles that pass a specific point in space, measured in hertz (cycles
per second)
Amplitude (a) - magnitude of wave's displacement, it's one half the height between peaks and troughs.
How high are the peaks from the midpoint?
More frequency = less wavelength (inversely proportional)
Speed of light (c) is constant
c = 2.998 x 108 m/s (in a vacuum)
c= λ × ν
λ=c/ν
ν=c/λ
Electromagnetic Spectrum is a range of energies that electromagnetic radiation can comprise.
Radio, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays.
The wave-particle duality
Waves = reflection and refractions (Huygens), light passing through slits (Young), electromagnetic
radiation (Maxwell)
Particles = lenses and prisms (Newton), blackbody radiation (Planck), photoelectric effect (Einstein)
Isaac Newton - light might be made of particles (seen through a prism)
Christiaan Huygens - behavior can only be explained as waves through reflection and refraction
Thomas Young - screen with two slits, if light were a particle he would've seen two slits, he saw light as a
wave, with multiple slits.
James Maxwell - first full color photograph electric and magnetic component.
Matter composed of particles moving according to Newton's laws of motion
Electromagnetic radiation consisting of waves governed by Maxwell's equations.
Elementary particles can exhibit both wave-like and particle-like properties.
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Paradoxes:
Maxwell Planck - Blackbody radiation, they absorb all light. As a body emits light, we can see the color in
the infrared range, not in the UV range. UV catastrophe.
He explained it as a particle.
E (energy) = n (number of light particles) × h (constant) × ν (frequency)
Planck's constant
h = 6.626x10-34 Js
Einstein - photoelectric effect. Electrons were ejected when light was shot at high energy.
Frequency was related to intensity, not energy, light should be viewed as a stream of particles, later
called photons.
Modified Planck's equation.
E in joules
1 - 6.71x10-7m
2 - 2.31x105 Hz
3 - 4.50 x10-28J
4 - 1.77x10-14J
The Bohr model (planetary)
The electrostatic force attracting an electron to the proton depends on the distance between the two
particles.
Ground state - electrons in an atom, ion, or molecule have the lowest energy possible.
Excited state - having energy greater than the ground state energy.
Energy is added to an electron, moves it to excited state, then electron moves to the ground state and
energy is released as a photon.
Energy of light should be equal to energy of electron.
messages.downloaded_by
Module II
lunes, 13 de enero de 2025
12:11 p. m.
The Nature of Light - Light interacts with matter.
Waves an oscillation or periodic movement that can transport energy from one point to another.
Electromagnetic waves consist of both electric and magnetic field, oscillating perpendicular to one
another. Both travel in the same direction.
Wavelength (λ - lambda) - distance between two peaks or troughs, measured in meters.
Can be measured from the top (peak) or bottom (trough) of the wave.
Frequency (ν - nu) - number of wave cycles that pass a specific point in space, measured in hertz (cycles
per second)
Amplitude (a) - magnitude of wave's displacement, it's one half the height between peaks and troughs.
How high are the peaks from the midpoint?
More frequency = less wavelength (inversely proportional)
Speed of light (c) is constant
c = 2.998 x 108 m/s (in a vacuum)
c= λ × ν
λ=c/ν
ν=c/λ
Electromagnetic Spectrum is a range of energies that electromagnetic radiation can comprise.
Radio, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays.
The wave-particle duality
Waves = reflection and refractions (Huygens), light passing through slits (Young), electromagnetic
radiation (Maxwell)
Particles = lenses and prisms (Newton), blackbody radiation (Planck), photoelectric effect (Einstein)
Isaac Newton - light might be made of particles (seen through a prism)
Christiaan Huygens - behavior can only be explained as waves through reflection and refraction
Thomas Young - screen with two slits, if light were a particle he would've seen two slits, he saw light as a
wave, with multiple slits.
James Maxwell - first full color photograph electric and magnetic component.
Matter composed of particles moving according to Newton's laws of motion
Electromagnetic radiation consisting of waves governed by Maxwell's equations.
Elementary particles can exhibit both wave-like and particle-like properties.
messages.downloaded_by
, lOMoARcPSD|64109549
Paradoxes:
Maxwell Planck - Blackbody radiation, they absorb all light. As a body emits light, we can see the color in
the infrared range, not in the UV range. UV catastrophe.
He explained it as a particle.
E (energy) = n (number of light particles) × h (constant) × ν (frequency)
Planck's constant
h = 6.626x10-34 Js
Einstein - photoelectric effect. Electrons were ejected when light was shot at high energy.
Frequency was related to intensity, not energy, light should be viewed as a stream of particles, later
called photons.
Modified Planck's equation.
E in joules
1 - 6.71x10-7m
2 - 2.31x105 Hz
3 - 4.50 x10-28J
4 - 1.77x10-14J
The Bohr model (planetary)
The electrostatic force attracting an electron to the proton depends on the distance between the two
particles.
Ground state - electrons in an atom, ion, or molecule have the lowest energy possible.
Excited state - having energy greater than the ground state energy.
Energy is added to an electron, moves it to excited state, then electron moves to the ground state and
energy is released as a photon.
Energy of light should be equal to energy of electron.
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