λ = 3 x 10^8 meters per second/ f ( cycles/per second) = 3 x 10^8/f meters/ cycles
The λ of a 60 Hertz ac signal is 3 x 10^8 meters/60 = 5 x 10^6 m this is around 3,100 miles
The λ of a 100 mega Hertz signal is 3 meters = 3 x 10^8/(1 x 10^8)
Light is usually measured in wavelength, visible light is measured in nanometers or angstroms. A 650 nm (6,500 angstrom) wavelength has a frequency of
f = c/λ = 3 x 10^8/6.5 x 10^-9 = 4.62 x 10^16 Hertz
the quantities of wavelength, wave velocity and wave frequency are all directly observable.
Frequency is how many times it oscillates in a second.
Wavelength is, if you freeze time and take a snapshot, the distance between two peaks of the wave.
There are multiple definitions of wave speed -- phase velocity, group velocity and energy velocity. Phase velocity is this: if you stick to a peak of the wave, that is how fast you must travel to stay with that peak. Sometimes this can be faster than the speed of light (but that doesn't violate relativity because phase doesn't carry energy).
Group velocity is this: if you send a wave packet with a range of frequencies, like a pulse, then how fast the center of the pulse moves is the group velocity. This is how fast information travels and will always be less than or equal to the speed of light. It is different than phase velocity in the presence of dispersion, where the speed changes with frequency.
Energy velocity is much like group velocity, only it measures where the energy travels. For electromagnetic waves, it is identical to group velocity.
Frequency*wavelength = speed of light.
that means that wavelength = speed of light/frequency. Not the other way around.
speed of light is in meters/second
frequency is in Hertz, which is seconds^(-1) or 1/seconds
wavelength is in meters.
so when speed of light (m/s) is divided by frequency (1/seconds), you flip the units of frequency and then multiply. So your units are:
(meters/second)(seconds) so the seconds cancel and you get meters.
The equation for any harmonic wave is:
Velocity = Wavelength*Frequency
Velocity is not necessarily that of light. For example, it could be velocity of sound.
Your equation is up side down. L=C/f, where C=3x10^8 meter/sec. Therefore the units of L are
(meters/sec)/(cycles/sec)=meters/cycle or just meters.
I know that wavelength = frequency / speed of light , but where's the unit of measurement for the wavelength come from? I realize that frequency means 'cycles per second', that is a unit of measurement, but gives?
