1
\$\begingroup\$

I am looking for formula and easy explanation for calculating the wavelength of a sine wave. So far I have not been able to calculate the example I want to do as I could not understand the resources I've found from Google.

What is the wavelength of sine wave? Given frequency, distance and time.

For instance, a 0.42 MHz sine wave takes 3.3 µs to travel 2500 meters.

I am asking for patience I know this might look amateur for some but I am learning basics and I struggle to find the answer.

\$\endgroup\$
2
\$\begingroup\$

$$speed = \frac{distance}{time \; to \; traverse \; it} $$

$$= \frac{2500}{3.3 \times 10^{-6}} \cdot \frac{[m]}{[s]} = 7.58 \times 10^8 m/s$$

That's physically impossible - it's faster than the speed of light (\$3 \times 10^8 m/s\$). Check again what the speed of the signal should be.

anyway, once you find it:

$$wavelength = \frac{speed}{frequency}$$

\$\endgroup\$
  • \$\begingroup\$ I guess its just example for getting use to formulas, there was never tought put into it \$\endgroup\$ – corkalom Nov 19 '14 at 20:52
  • \$\begingroup\$ 1804m/s I totally confused I was used to work with nano meters \$\endgroup\$ – corkalom Nov 19 '14 at 21:09
2
\$\begingroup\$

The wavelength is $$\lambda = \frac{v}{f}$$

where \$v\$ is the velocity of the wave and \$f\$ is the frequency. Here you have $$v = \frac{2500\text{m}}{3.3\mu\text{s}}$$

Just be sure to convert \$v\$ to m/s and \$f\$ to Hz so the units work out. \$\lambda\$ is in meters.

\$\endgroup\$
0
\$\begingroup\$

Using λ=v/f

assuming it is a standard electromagnetic wave (not a sound wave):

300/.42=714.2857142857143m, or 809.5238microns (peak-to-peak or crest-to-crest)

Where v is the velocity of the wave (default is velocity of light in vacuum: 300.000 Km/s).

[This answer is technically more correct (v=299,792,458 m/s): 713.79m]

\$\endgroup\$
0
\$\begingroup\$

Expanding on Answer #1 above

or if you're going through some odd medium (Jello maybe?):

Using λ=v/f

λ=(2500m/0.0000033sec)/420000Hz=1803.7518m

1 meter = 1 000 000 000 nanometers (1,803,751,800,000nM)

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.