Electromagnetic Spectrum
Electromagnetic Spectrum: Grouping of radiate energies, including:
Radio waves
Microwaves
Infrared
Visible light
Ultraviolet
X-rays
Gamma rays
Electromagnetic Radiation: Defined as energy disturbances traveling at the speed of light (3.0 x 10^8 m/s).
Consists of electric and magnetic fields.
Emitted by atoms during changes in electron orbits.
Mechanical Energy Analogy:
Dropping a pebble creates waves in water (kinetic energy).
Sound waves created by drum vibrations transfer energy through air molecules.
Nature of Electromagnetic Radiation:
Vibration of an electromagnetic field.
Does not need a medium to travel.
Wave Characteristics:
Speed (constant for all EM radiation)
Amplitude (height of a wave, larger means stronger)
Wavelength (distance from peak to peak)
Frequency (number of waves per second)
Wavelength and Frequency Relationship:
Inverse relationship: longer wavelength = lower frequency, shorter wavelength = higher frequency.
Frequency expressed in Hertz (Hz).
Wave Formula: c = fλ (where c is speed of light, f is frequency, λ is wavelength).
Examples: 1) [ f = \frac{c}{\lambda} ] 2) [ \lambda = \frac{c}{f} ]
Summation of Electromagnetic Spectrum:
Continuous range of wavelengths and frequencies.
Different forms of EM energy (light, radio waves, X-rays) merge seamlessly.
Review Questions:
Highest frequency = shortest wavelength.
Distance between wave peaks = wavelength.
Lowest energy (from microwaves, visible light, infrared, gamma rays) = microwaves.
Speed refers to wave velocity.
All EM radiation is an electric and magnetic disturbance at speed of light.
The electromagnetic field vibrates in EM radiation, not the medium.
Example problem: Frequency for wavelength of 3 x 10^12 m = [ f = \frac{3 x 10^8 m/s}{3 x 10^{12} m} = 1 x 10^{-4} s ]