Applications of Electromagnetic Waves

Wave polarization

direction of oscillation of a wave

Polaroid filters

absorb light polarized in a particular direction, composed of microscopically thin slits

Parallax

difference in the apparent position of an object when seen from different lines of sight

Heinrich Hertz

came up with the idea to send a wireless signal

Guglielmo Marconi

invented the wireless telegraph

Radio telescopes

telescope that focuses radio waves to collect or send signals

Arecibo

one of the largest radio telescopes ever built, located in Puerto Rico

Cosmic Microwave Background

leftover radiation from the birth of the universe that has cooled down to the microwave part of the electromagnetic spectrum

James Webb Space Telescope

largest space telescope ever built, launched in December 2021, detects infrared radiation

Amplitude modulation (AM)

method of converting kHz sound into MHz radio waves; amplitude of the radio wave is varied in proportion to the frequency of the sound wave

RLC circuit

responds to a certain frequency of electromagnetic wave depending on how you tune it

Frequency modulation (FM)

frequency varies with the frequency of the sound

Cathode ray tube (CRT)

used by early televisions to produce images; electrons emitted by cathode are accelerated via high voltages to anode, pass through a magnetic field and are deflected onto a phosphorescent screen

Cathode

collection of negative charge, emits electrons

Anode

collection of positive charge

Liquid crystal display (LCD)

each pixel as two glass plates (polarizers) with a gooey material in between; when voltage is applied, all the liquid crystals line up so light can’t pass through second plate

Cones

eye cells that are sensitive to red, green, and blue

Light-emitting diodes (LEDs)

more efficient alternative to incandescent lightbulbs; use semiconductors

Diode

circuit component that only allows current to flow through in one direction

Semiconductors

mixture of two materials that are normally not good conductors but can act as a conductor when they are combined and exposed to an external voltage

Solar panels

semiconductors absorb sunlight, electrons are freed to the conducting shell, allowing for the flow of current

Light sail

large sheet of reflective material that can catch sunlight, potential way to power spacecrafts; slow acceleration but could reach high speeds after enough time