Electromagnetic Waves Flashcards
Is the time for one wavelength to pass a point.
Period (T)
Is the speed at which a specific part of the wave passes a point.
Velocity (V)
Two types of Waves
Transverse Waves and Longitudinal Waves
- Is a disturbance in a medium that carries energy without a net movement of particles.
- It may take the form of elastic deformation, a variation of pressure, electric or magnetic intensity, electric potential, or temperature.
Transfers energy. - Usually involves a periodic, repetitive movement.
- Does not result in a net movement of the medium or particles in the medium (mechanical wave).
Waves
Is the distance between two successive identical parts of the wave.
Wavelength
Is the maximum displacement from the neutral position.
This represents the energy of the wave.
Greater amplitude carries greater energy.
Amplitude
Is the number of repetitions per second in Hz
Frequency (F)
Is the position of a particular point in the medium as it moves as the wave passes.
Displacement
Waves in which the medium moves at right angles to the direction of the wave.
Transverse Waves
High point of a transverse wave
Crest
Lowest point of a transverse wave
Trough
A wave that has the movement of the particles in the medium in the same dimension as the direction of movement of the wave.
Longitudinal Waves
A part of the longitudinal wave where the particles are close together.
Compression
A part of the longitudinal wave where the particles are spread apart.
Rarefraction
Examples of Longitudinal Waves
- Sound waves
- P-type earthquake waves
- Compression wave
Examples of Transverse Waves
- Water waves (ripples of gravity waves, not sound through water)
- Light waves
- String Instrument
- Torsion waves
- S wave earthquake waves
- The higher the frequency, the higher the energy carried by the wave.
ELECTROMAGNETIC (EM) WAVES
- Cannot penetrate the cells of organisms. ex, microwaves, radio waves, infrared, visible light, UV rays
NON-IONIZING RADIATION
can penetrate the cells of organisms. It can cause biological damage.
ex. Xrays, Gamma rays
IONIZING RADIATION
⚫ are the region in the EM spectrum with the longest wavelength and lowest frequencies.
* Wavelengths: 1 cm to 1 km
* Frequencies: 30 gigahertz to 300 kilohertz.
Television and FM and AM radio broadcasts, military communications, mobile phones, ham radio, wireless computer networks, and numerous other communications applications.
RADIO WAVES
⚫ with frequencies less than 3KHz and wavelengths greater than 100 km.
* also known as myriameter band
⚫ used for military communications with submarines because of the ability to penetrate saltwater up to certain depths.
Wireless transmission of sound messages, or information, for communication, as well as for maritime and aircraft navigation.
* Naturally generated in the atmosphere.
Extremely low frequency waves
⚫ with frequency 30 to 300 KHz and wavelengths ranging from 1m to 10 km
⚫ used for long distance
communication.
Low frequency waves
⚫ with frequencies ranging from 300 kHz to 3 MHz and wavelengths from 100m to 1 km.
⚫ used for amplitude modulation (AM) broadcasting and air traffic control.
Medium-frequency waves
⚫ with frequencies ranging from 3 to 30 MHz and wavelengths ranging from 10 to 100m.
* used for international broadcasting.
High-frequency waves
⚫with frequencies ranging from 30
to 300 MHz and wavelengths ranging from 1 to 10m.
⚫ used for digital audio
broadcasting and mobile radio systems.
Very high-frequency waves
⚫ with frequencies ranging from 300 MHz to 3 GHz and wavelengths ranging from 1cm to Im.
⚫ used for TV broadcasting, GPS, Wi- Fi, Bluetooth.
Ultra high-frequency waves
- Frequency: 300 MHz to 300
GHz. - Sub-bands: L,S,C,X, and K.
- L-bands used for GPS.
- Other bands are used for RADAR systems.
Micro-wave
- Frequency: 3 x 10^11 to 4 x 10^14 Hz
- Grouped into: Near, mid, and far infrared regions.
- Invisible to an unaided eye but can be detected in the form of heat.
- In 1800, William Herschel first recorded the thermal
measurement at the far end of the red spectrum. - Used in remote sensing.
- the remote controls of the TV sets use IR to send signals to change
channels.
used in thermal imaging.
INFRARED
*The part of the EM spectrum that can be seen by the naked eye.
* Frequency: 400 to 700mm
* Spectral Signatures: patterns of dark lines and colors, used in identifying structure and composition of substances.
VISIBLE LIGHT
- In 1801, John Ritter successfully proved the existence of energy beyond violet spectra.
- Wavelength: 10 to 400mm
ULTRAVIOLET WAVES
UVA
Least Harmful
UVB
Can cause sunburn
UVC
Most harmful but is absorbed by the ozone layer
- First observed by Wilhelm Conrad Roentgen in 1895.
- The wavelengths are small,
energies carried are described in electron volts (eV) - Soft Xrays carry smaller amounts of energy compared to hard
Xrays. - These energy allows them to penetrate through matter.
X - RAYS
- found at the end of the EM Spectrum.
⚫ contains the highest energy of all.
⚫ are produced by objects with very high
energy.
GAMMA RAYS
Wave that need medium to propagate
Mechanical wave
Wave that doesnt need medium to propagate
Em waves
