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--- demonstrations:6_optics:6d_interference:interference_fringes_in_a_soap_bubble:start [2019/01/31 23:10]
127.0.0.1 external edit
+++ demonstrations:6_optics:6d_interference:interference_fringes_in_a_soap_bubble:start [2020/03/16 17:20] (current)
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 ====== Interference Fringes In A Soap Bubble ======
-{{tag>bubbles needs_review untagged unlocated}}
+{{tag>bubbles interference waves light surface_tension located}}
 <WRAP box right>
-{{InterferenceFringesInASoapBubble_006.jpg?400|}}
+{{img_20190212_155058.jpg?400|}}
-// //
+// Example of the interference patterns visible using solution no.2 //
 </WRAP>
 ===== Description =====
-Thin film interference    Classes Used: PHYS 101, PHYS 158
+Colorful and visually interesting demonstration showing the interference pattern produced by light reflecting off of a soap bubble.
+===== Purpose =====
-interference
+To show the interference fringes produced by a thin soap bubble.
+===== Apparatus =====
-===== Purpose =====
+In box labeled 'Thin Film Soap Bubble':
+  * 10cm diameter ring
+  * lens
+  * clamp for ring
+  * solution
+  * Yellow filter
-To show the interference fringes produced by a thin soap bubble.
+Additionally:
+  * [[equipment:35mm_projector:start|35 mm projector]]
+  * A pair of [[equipment:lab_stands:start|lab stands]]
+===== Setup =====
-===== Apparatus =====
+A solution is made out of dish soap, water, and glycerin (to help prolong the life of the bubble). The metal ring is dipped into the solution (a pie plate works well to hold it) and placed into the test stand. The projector is aimed at the bubble film and the reflection is focused onto a distant screen using the lens.
-Metal ring and solution, Lens, 35 mm projector, various stands and clamps, coloured filters.
+Optionally, you can put the yellow filter in the projector. Then instead of seeing a multicolored interference pattern, a yellow and black pattern will be visible. This may be easier to explain than the multicolored pattern, though it'll be less pretty.
+===== Bubble Solution Recipes =====
+These recipes were made for use with the 10cm diameter ring currently included in the box. For smaller or bigger sizes of bubbles a different solution may be desired.
-===== Setup =====
+Some notes on mixing your own: Start with just water and soap. A 50-50 mixture works okay on it's own, but is short lived (~10 seconds). Adding glycerin to the mixture will make the bubble last much longer. The water to glycerin ratio determines how quickly the interference pattern will develop. More glycerin, and it'll take much longer to show. More water and it'll develop much faster, and the horizontal banding due to gravity will also be much more apparent.
+Presidents Choice 'Ultra Original 2X' dish soap was used for mixing these.
-A solution is made out of dish soap, water, and glycerin to help prolong the life of the bubble. The metal ring is dipped into a soap solution and the projector light is directed on to the soap bubble and the reflection is focused on the wall using a lens. With white light, coloured horizontal fringes can be seen. With the yellow filter a series of yellow and black fringes are seen of varying width as the soap bubble drains leaving the thinnest film at the top.
+=== Bubble Solution No. 1 ===
+//Interference pattern shows pretty quickly. Somewhat long lived. Horizontal banding due to gravity is strongly evident.//
+  * 300 mL water
+  * 75 mL dish soap
+  * 30 mL glycerin
-===== Notes =====
+=== Bubble Solution No. 2 ===
+//Interference pattern develops more slowly. Very long lived (hours). Some horizontal banding is evident, but since the solution is much thicker it's less dominant. Much greater degree of swirling and complicated shapes.//
-Students must be reminded that the lens has inverted the image. The thinnest portion of the film will therefore be seen at the bottom on the screen as an extended black area just before the bubble breaks.
+  * 300 mL water
+  * 100 mL dish soap
+  * 100 mL glycerin
-General Location:
+===== Notes =====
-There are many parts for this demo and nothing is specifically set aside. There are many pictures below that will hopefully aid in constructing this demonstration. This demonstration could be made with simple house-hold products. The projector is found in the blue closet floor. Clamps and such can be found at the back of the room, while glycerin can be found in the fume hood.     Updated on: 01/13/17
+Students must be reminded that the lens has inverted the image. Depending on the solution you use, the thinnest portion of the film will therefore be seen at the bottom on the screen as an extended black area just before the bubble breaks.
 <WRAP group>
 <WRAP half column>
+<WRAP box right>
+{{solution1.mp4?400|}}
+// Formation of interference patterns visible using solution no.1. //
+</WRAP>
 </WRAP>
@@ Line 63: / Line 90: @@
 </WRAP>
 <WRAP tablewidth 100%>
-| **Location** | ---- |
+| **Location** | A4 |
 | **Maker** | Unknown |
 | **Current State** | Working |

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