Posted by **Mary** on Wednesday, November 14, 2007 at 9:36am.

Can you please explain your answer. How did you get blue lamda. Is it because red and green makes blue? How do I find the value of blue lambda?

A mixture of red light (vacuum = 661 nm) and green light (vacuum = 551 nm) shines perpendicularly on a soap film (n = 1.35) that has air on either side. What is the minimum nonzero thickness of the film, so that destructive interference causes it to look red in reflected light?

nm

For Further Reading

Physic please help! - bobpursley, Wednesday, November 14, 2007 at 7:30am

Wouldnt the thickness be blue lamda/4? ?

- Physics please explain -
**drwls**, Wednesday, November 14, 2007 at 10:00am
Bob may have meant to say green light, not blue. The wavelength requirement for minimum reflection is given at

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/soapfilm.html

For normal incidence and first order destructive interference of reflected green light,

2 N d = lambda(green)

N is the index of refraction.

- Physics please explain -
**bobpursley**, Wednesday, November 14, 2007 at 11:41am
I meant green. Sorry.

## Answer This Question

## Related Questions

- 7th grade math (probability) - I'm posting corrections from yesterday in ...
- 7th grade math (probability) - I'm re-posting corrections originally from ...
- math-algebra - 7. A bag contains 5 red marbles, 6 green marbles, and 9 blue ...
- statistics - A die has 2 red faces, 2 blue faces, and 2 green faces. It is ...
- math - A bag contains the following marbles:6 red,4 orange,3 yellow,2 blue and 5...
- Biology - Two purple flowers (Bb) are bred with each other in the same garden. ...
- Math - An artist mixes blue and yellow to make a shade of green. The ratio of ...
- 7th grade math - Can you check this problem? Jean has 5 different colors of ...
- math - sally has a bag with red,blue, and green marbles. She has twice as many ...
- math (rate) - A blue candle is twice as long as a red candle. The blue candle ...

More Related Questions