Physics quiz archive: electromagnetic waves, polarization, reflection/refraction

Physics 205B Quiz 1, spring semester 2020
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz01PxP7



Sections 30882, 30883 results

0- 6 :	* [low = 6]
7-12 :	**
13-18 :	*********
19-24 :	*********** [mean = 21.9 +/- 5.9]
25-30 :	************ [high = 30]

Physics quiz archive: electromagnetic waves, polarization, reflection/refraction

Physics 205B Quiz 1, spring semester 2019
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz01aN7u




Sections 30882, 30883 results

0- 6 :	* [low = 3]
7-12 :	****
13-18 :	*******
19-24 :	***************** [mean = 20.8 +/- 5.7]
25-30 :	******** [high = 27]

Physics quiz archive: electromagnetic waves, polarization, reflection/refraction

Physics 205B Quiz 1, spring semester 2018
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz01AM0l




Sections 30882, 30883 results

0- 6 :
7-12 :	* [low = 9]
13-18 :	****
19-24 :	**********
25-30 :	************** [mean = 24.7 +/- 4.9] [high = 30]

Physics quiz archive: electromagnetic waves, polarization, reflection/refraction

Physics 205B Quiz 1, spring semester 2017
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz01Om6A


Sections 30882, 30883 results

0- 6 :
7-12 :	**** [low = 9]
13-18 :	**********
19-24 :	******* [mean = 19.7 +/- 6.0]
25-30 :	******* [high = 30]

Physics quiz archive: electromagnetic waves, reflection/refraction

Physics 205B Quiz 1, spring semester 2016
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz01sN0w



Sections 30882, 30883 results

0- 6 :	*** [low = 6]
7-12 :	**
13-18 :	************
19-24 :	****************** [mean = 20.7 +/- 6.1]
25-30 :	******** [high = 30]

Physics quiz archive: electromagnetic waves, reflection/refraction

Physics 205B Quiz 1, spring semester 2015
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz01c0Co



Sections 30882, 30883 results

0- 6 :	*** [low = 6]
7-12 :	***
13-18 :	***********
19-24 :	************************* [mean = 19.9 +/- 5.7]
25-30 :	****** [high = 30]

Physics quiz archive: electromagnetic waves, reflection/refraction

Physics 205B Quiz 1, spring semester 2014
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz01ksB4



Sections 30882, 30883 results

0- 6 :
7-12 :	* [low = 9]
13-18 :	***********
19-24 :	****************** [mean = 22.6 +/- 5.0]
25-30 :	*********** [high = 30]

Physics quiz archive: electromagnetic waves, reflection/refraction

Physics 205B Quiz 1, spring semester 2013
Cuesta College, San Luis Obispo, CA
Section 30882, version 1
Exam code: quiz01b3Es



Section 30882 results

0- 6 :	* [low = 6]
7-12 :	****
13-18 :	**************
19-24 :	************ [mean = 19.1 +/- 5.9]
25-30 :	**** [high = 30]

Physics quiz archive: electromagnetic waves, reflection/refraction

Physics 205B Quiz 1, spring semester 2012
Cuesta College, San Luis Obispo, CA

Section 30882, version 1
Exam code: quiz01pL2r
Section 30882 results
Quiz 1 results (max score = 30):

0- 6 :
7-12 :	** [low = 9]
13-18 :	**********
19-24 :	***** [mean = 22.4 +/- 6.5]
25-30 :	************ [high = 30]

Physics quiz archive: electromagnetic waves, reflection/refraction

Physics 205B Quiz 1, Spring Semester 2011
Cuesta College, San Luis Obispo, CA

Section 30882, version 1

Section 30882 results

 0- 6 : 
 7-12 : 
13-18 : ***  [low = 15]
19-24 : **  [mean = 22.9 +/- 5.3]
25-30 : ***  [high = 30]

Online homework assignment: destructive thin film reflections

Physics 205B Homework Assignment 4, Spring Semester 2010
Cuesta College, San Luis Obispo, CA

Cf. Giambattista/Richardson/Richardson, Physics, 2/e, Problem 25.17

A thin film of oil (n = 1.50) of thickness 0.40e-6 m is spread over a puddle of water (n = 1.33). The two visible wavelengths that will destructively interfere for reflection will have values of __________ nm and __________ nm in air. (Visible wavelengths in air are in the range of 400 nm to 700 nm.)

Correct answer: 400 nm, 600 nm.

Light in air reflects off of the top of the oil film with a 180 degree phase shift ("fast off of slow"). Light in oil reflects off the top of the water with no phase shift ("slow off of fast"). The two reflections are out of phase.

For destructive interference of these two out of phase reflections, the path difference condition is:

delta(l) = m*lambda_oil,

where the path difference between the two reflected waves is twice the thickness of the oil film, or 2*t, and lambda_oil is related to the lambda_air wavelengths in air:

lambda_oil = lambda_air/n_oil,

as wavelengths are shorter in slower media, compared to the longest in air (or vacuum).

Substituting delta(l) = 2*t, and lambda_oil = lambda_air/n_oil into the destructive interference condition for out of phase reflections:

2*t = m*(lambda_air/n_oil),

2*t*n_oil/m = lambda_air,

with m = 0, 1, 2, 3, 4, ..., possible wavelengths in air that would destructively interfere would be infinite, 1200 nm, 600 nm, 400 nm, 300 nm, ..., respectively, of which only 400 nm and 600 nm are in the visible range in air.

Student responses
Section 31988
537 nm, 637 nm: 1 response
400 nm, 600 nm: 2 responses
429 nm, 687 nm: 1 response
(Blank/no work submitted: 9 responses)