Module 1: Nature of Light Flashcards
Electromagnetic Spectrum
Continuous band of energy divided into 7 regions Visible and UV used most in lab In order of increasing wavelength: gamma rays X rays Ultraviolet (180-380nm) visible (380nm-780nm) infrared microwaves radiowaves
Electromagnetic radiation properties
1) travel in waves
2) Interacts with matter as particles
Dual nature of light
Light is a massless particle that travels in a wave-like form
(both a particle and a wave)
Photon
massless particle that contains a certain amount of energy
Characteristics of Light waves
Wavelength
Amplitude
Frequency
Velocity
Wavelength (λ)
Distance between 2 consecutive peaks in the wave pattern
Expressed in nanometers (nm)
Amplitude (A)
Total wave height (from trough to peak) which relates to the intensity
Frequency (f)
Number of wave cycles passing a given point per second
Velocity (v or c)
Speed of light
Varies depending on the medium the light wave is traveling through
Energy of a photon is determined by:
the wavelength (and frequency) of the light
High energy photon
Light with a short wavelength and high frequency
Low energy photon
Light with a long wavelength and low frequency
White light
When all visible light wavelengths are present
Polychromatic
Light consisting of all or a portion of the wavelengths of the spectrum
Monochromatic
Light of one wavelength
Manipulations of light (5)
Reflection Refraction Diffraction Interference Polarization
Reflection
The change in direction of a wave of light due to interaction with a reflecting surface (mirror, water surface, shiny metals)
Refraction
Bending of light rays
Change in medium density (from one medium to another) alters the velocity of the light
Shorter wavelengths are refracted more than longer wavelengths
Diffraction
As light passes through a slit or narrow opening, it is bent by the edges of the slit
Interference
Result of light waves interacting with each other
Interference “in phase”
Light waves that are synchronized (peaks and troughs match)
Interfere constructively, reinforcing each other and increasing intensity
Interference “out of phase”
Light waves that are not synchronized
Interfere destructively resulting in lower intensity or cancelling each other out
Polarization
Passing unpolarized ray of light through special lens or crystal, only one plane of orientation may be selected
Polarized light
Light that is orientated in only one plane
Unpolarized light
Light that is orientated in multiple planes
