# Can any type of wave produce an interference pattern from two sources?

Can any type of wave produce an interference pattern similar to the one in a double slit experiment? So for example, could a radio wave create an interference pattern through the airwaves?

• If the wave consists of a single frequency, and if the slits are small enough to allow for this effect to be noticeable, then yes. Aug 1, 2018 at 12:12
• If they are linear waves, then yes. Aug 1, 2018 at 14:13
• radio wise, there is "multipath fading". It's the young double slit where your radio is the screen, and there's more than one path from the transmitter to the radio.
– JEB
Aug 1, 2018 at 14:29

The only requirement for wave interference is the principle of superposition:

$$W(x,t) = W_1(x,t) + W_2(x,t)$$

That is, the total wave amplitude is simply the sum of the amplitudes of the other interfering waves. This condition, along with the condition that the two sources start in phase, are the only requirements needed to describe an interference pattern such as from a double-slit experiment.

Radio waves obey they law of superposition, and so you could perform a double-slit experiment with them.

• Do the sources have to start in phase for an interference pattern to occur? Wouldn't a phase difference between the two sources just shift the interference pattern? Aug 1, 2018 at 13:04
• You are correct: phase differences at the slits (ie source) would produce a skewed interference pattern. Most double slit experiments are designed to eliminate phase differences, since it produces the simplest pattern.
– cms
Aug 1, 2018 at 13:11
• Monopolar pulses do not exhibit interference in the normal sense. Aug 1, 2018 at 17:40
• A clarification here is that you still need the source to be coherent and monochromatic--only one frequency/wavelength. Sound waves can interfere as well. If you have a pair of stereo speakers and play a pure sine tone over them, they will produce an interference pattern (you have to plug one ear to notice). However, you will rarely notice this playing music because music is a mix of many different frequencies, and so at any one point in space only a handful of frequencies will cancel out. Apr 4, 2020 at 4:24

The only necessary condition for interference is that the sources must be coherent (constant phase difference and same wavelength). It is impossible for two independent sources to be perfectly coherent as there will always be random variations in the emission of the photons. Hence it is impossible to produce a sustained interference pattern with two sources.

Yes any two wave can interfere having same nature like we can do double slit experiment through the sound wave, for two wave to show interference pattern, phase difference should be constant what I am saying is this.)

Consider say two electromagnetic wave, whose phase difference changes with time.

$$E_1=E_0sin(wt_1-kx)$$,and $$E_2=2E_0sin(wt_2-kx)$$,

And for phase difference.

$$(wt_1-kx) - (wt_2-kx) =H$$ (where H is phase difference).

it is very difficult to know how they wave interfere at that particular instant.beacuse of their phase changes with time. So conclusion is

two similar wave (wave have same kind of nature) can interfere to produce resulting wave, where $$A$$ will be the resultant amplitude, two sources should be coherent.