QueryAssignment21

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course Phy 232

Your solution, attempt at solution. If you are unable to attempt a solution, give a phrase-by-phrase interpretation of the problem along with a statement of what you do or do not understand about it. This response should be given, based on the work you did in completing the assignment, before you look at the given solution.

021. `Query 19

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Question: `qPrinciples of Physics and General College Physics Problem 24.54: What is Brewster's angle for an air-glass interface (n = 1.52 for glass)?

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Your solution:

Brewster’s angle can be found because we know the relationship of the angle, along with the index of refraction for glass and air. The index of refraction for air is 1 and the index of refraction for glass is 1.52, which is given. Using the equation tan(theta) = n2 / n1 can allow us to solve for the angle. N2 is the index of refraction for glass and n1 is the index of refraction for air. After setting this equation up we get,

Tan(theta) = (1.52) / (1).

Therefore the angle comes out to equal arctan(1.52) = 15.66 degrees.

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Given Solution:

`aBrewster's angle is the smallest angle theta_p of incidence at which light is completely polarized. This occurs when tan(theta_p) = n2 / n1, where n2 is the index of refraction on the 'other side' of the interface.

For an air-glass interface, n1 = 1 so tan( theta_p) = n2 / 1 = n2, the index of refraction of the glass. We get

tan(theta_p) = 1.52 so that

theta_p = arcTan(1.52). This is calculated as the inverse tangent of 1.52, using the 2d function-tan combination on a calculator. WE obtain

theta_p = 56.7 degrees, approximately.

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Self-critique (if necessary): OK

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Self-critique Rating: OK

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Question: `qgen phy problem 24.44 foil separates one end of two stacked glass plates; 28 lines observed for normal 670 nm light

gen phy what is the thickness of the foil?

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Your solution:

If there are 28 dark lines, then there are 27 intervals present. This number is represented by m = 27. Using the equation 2*thickess = m*lambda, we can solve for the thickness of the foil.

2*thickness = (27)*(670 nm)

Thickness = (1/2)*(27)*(670 nm)

Thickness = 9,045 nm.

confidence rating #$&*:

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Given Solution:

`aSTUDENT SOLUTION: To solve this problem, I refer to fig. 24-31 in the text book as the problem stated. To determine the thickness of the foil, I considered the foil to be an air gap. I am not sure that this is correct. Therefore, I used the equation 2t=m'lambda, m=(0,1,2,...). THis is where the dark bands occur .

lambda is given in the problem as 670nm and m=27, because between 28 dark lines, there are 27 intervals.

Solve for t(thickness):

t=1/2(27)(670nm)

=9.05 *10^3nm=9.05 um

INSTRUCTOR RESPONSE WITH DIRECT-REASONING SOLUTION:** Your solution looks good. Direct reasoning:

** each half-wavelength of separation causes a dark band so there are 27 such intervals, therefore 27 half-wavelengths and the thickness is 27 * 1/2 * 670 nm = 9000 nm (approx) **

**** gen phy how many wavelengths comprise the thickness of the foil?

GOOD STUDENT SOLUTION: To calculate the number of wavelengths that comprise the thickness of the foil, I use the same equation as above 2t=m'lambda and solve for m.

2(9.05 um)=m(6.70 *10^-7m)

Convert all units to meters.

m=27 wavelengths.

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Self-critique (if necessary): OK

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Self-critique Rating: OK

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