Waves

Wave Properties and Patterns

Waves are not actual physical things, instead they describe a type of motion that transfers energy without needing to move mass around with it (usually from a vibration). For example, a beach ball in the ocean does not move along with the water, it instead will bob up and down as waves travel underneath it. When doing this type of movement a few patterns are possible:

Transverse waves are the pattern of wave you see in math classes. They make an up and down or side to side pattern.

Longitudinal waves are a pattern of wave where there are regions of activity, it looks like it compresses and stretches out as the wave moves.

Surface waves do both other patterns at once which makes a rolling motion as it moves forwards.

Types of Waves

Mechanical waves are a disturbance that travels through a medium (such as air, earth, or water), while Electromagnetic waves are the waves that transfer through radiation. Electromagnetic waves are always considered to be transverse and move at the speed of light.

Mechanical Waves

Electromagnetic Waves

Sound Waves

Earthquake Waves

Ocean Waves

X-Rays

Bluetooth

Wifi

Microwaves

Visible Light

Wave Functions

A wave has the following pieces:

Amplitude (a): How tall the wave is (from its center point).
Wavelength (λ): The length of the wave.
Frequency (f): How often the wave repeats itself (usually cycles per second).
Speed (v): How fast the wave is traveling.
Period: How long it takes to make one complete back and forth motion (it’s also 1 / f)

v = λ f

For electromagnetic radiation the speed the wave travels at is always 3 x 10^8 m/s (aka the speed of light). This speed is denoted by c in the formula below.

c = λ f

We can then use this information to see how much energy is being transmitted, with h being Plank's constant (a number that is always equal to 6.63 x 10^-34 J s) and E being energy:

E = h f

Light Waves

The full electromagnetic wave spectrum are considered light waves, with energy and wavelength size opposite to one another. Since these all travel at the speed of light the smaller waves need a lot more energy to travel the same distance due to how they wind around. We use these electromagnetic waves for many different technologies in the modern world for purposes of heating food, sending information, and even battling cancer! We also have ways to see into parts of the spectrum that we couldn't normally see with things like infrared glasses and UV lights.

Infrared is a type of radiation that we can see by converting its wavelengths into fake colors using technology!

The earth is constantly gaining and losing energy through radiation. Radiation is the only type of energy transfer that can go through the vacuum of space!

The Greenhouse Effect

Some sunlight gets trapped by gases in the atmosphere, bouncing back to earth and keeping heat in the atmosphere. This is known as the greenhouse effect. One of the greenhouse gases that people are most concerned with is carbon dioxide - a gas which forms from combustion (and thus is created whenever we burn fossil fuels).

More than just carbon dioxide is a greenhouse gas - as long as the gas reflects some of the electromagnetic spectrum it's considered one and will cause a greenhouse effect. Carbon dioxide, methane, and even water vapor are considered greenhouse gases.

Emergency Radio (PSA)

Radio frequencies are measured in Hertz (Hz) and range from kilohertz to Gigahertz. These bands of radio are each used for different types of messaging:

Some frequencies are used for emergencies to get information out to those who need it or allow quick communication between responders. These frequencies are generally in the HF, VHF, or UHF frequencies (though these specific frequencies vary from place to place).

Additional Resources

Wave Equation Practice

Interesting Links

Page updated

Report abuse