<p>The first image shows two waves in superposition. It shows how, in general, when two sinusoidal waves interfere the result is another wave with the same frequency but different amplitude and a phase shift.</p>
<p>And the second image shows destructive interference. I don't think it says that the first is &quot;destructive interference&quot; as it says, &quot;Destructive interference occurs when the maxima of two waves are 180 degrees out of phase&quot;, and in the first image the two waves are 90 degrees out of phase.</p>
<p>The first image is also used on the page &quot;Constructive interference&quot;. Again it shows two waves in a general superposition, and the second image shows constructive interference.</p>

CC BY-SA 4.0
2022-05-15T13:00:45.170Z
Why does it say “The images below show the effects of destructive interference”?
water castle
CC BY-SA 4.0
2022-05-15T13:11:18.093Z
They should change it to “interference”
water castle
CC BY-SA 4.0
2022-05-15T13:36:28.970Z
If you're confused then the Encyclopedia can't be very clear. However I'm not responsible for maintaining that page, so I can't do anything.  I suggest you contact the university.
James K
CC BY-SA 4.0
2022-05-15T05:21:36.397Z
2022-05-15T05:21:36.397Z
James K
<p>I was reading about <a href="https://astronomy.swin.edu.au/cosmos/D/Destructive+Interference" rel="nofollow noreferrer">destructive interference in the SAO Encyclopedia of Astronomy</a>. For some reason it says the first photo is destructive interference, when clearly, the amplitude increases, so it should be constructive interference. Is this a mistake in the encylopedia or am I missing some information? The second photo correctly shows destructive interference as they cancel to zero amplitude.</p>
<p><a href="https://i.sstatic.net/vNbIE.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/vNbIE.jpg" alt="enter image description here" /></a></p>

<astrophysics>
SAO Encyclopedia of Astronomy information
water castle
# SAO Encyclopedia of Astronomy information

(Asked by: username_0 on 2022-05-15)

I was reading about [destructive interference in the SAO Encyclopedia of Astronomy](https://astronomy.swin.edu.au/cosmos/D/Destructive+Interference). For some reason it says the first photo is destructive interference, when clearly, the amplitude increases, so it should be constructive interference. Is this a mistake in the encylopedia or am I missing some information? The second photo correctly shows destructive interference as they cancel to zero amplitude.

[![enter image description here](https://i.sstatic.net/vNbIE.jpg)](https://i.sstatic.net/vNbIE.jpg)

**Tags:** astrophysics

---

## 1 answers

### Answer by username_1 on 2022-05-15. Score: 0 | Accepted answer

The first image shows two waves in superposition. It shows how, in general, when two sinusoidal waves interfere the result is another wave with the same frequency but different amplitude and a phase shift.

And the second image shows destructive interference. I don't think it says that the first is "destructive interference" as it says, "Destructive interference occurs when the maxima of two waves are 180 degrees out of phase", and in the first image the two waves are 90 degrees out of phase.

The first image is also used on the page "Constructive interference". Again it shows two waves in a general superposition, and the second image shows constructive interference.

> **Comments:**
> **username_0**: Why does it say “The images below show the effects of destructive interference”?  
> **username_0**: They should change it to “interference”  
> **username_1**: If you're confused then the Encyclopedia can't be very clear. However I'm not responsible for maintaining that page, so I can't do anything.  I suggest you contact the university.  

---

