Question

Part B Lab Go to PhET website. Click on Simulation Physics. Under Physics, choose Light & Radiation. Under Light & Radiation, Bending Light is the 6th simulation (Location might change. A to Z search.) Click to run the Bending Light/More Tools. Complete Data Table with Bending Light/More Tools Simulation: Basic Operation for More Tools Simulation: Place check marks on Ray, Normal, and Angles. Keep the default setting Material 1 (above surface) index of refraction as air = 1.000 and Material 2 (below surface) Index of refraction as glass now. Adjust incident wavelength of light to = 700 nm. Press the Red Button of the light source. Using the defaut incident angle 0.45", record the refracted angle 02 and index of refraction om (under Material 2) to Data Table Test and understand all functional tools on screen You must practice figuring out what is the best way to complete the measurement Data Table 1: Measure Index of Refraction Keep incident angle 0. = 45° Vary incident wavelength (nm). Measure retracted anglez (") and index of refractionam in medium of glass. Calculate na by Snell's law, menisinsinde. Calculate speed of light in glass by, c/n (in unt of c. Exe 1.500, : = / 1.500 = 0.667c). C is speed of light in vacuum c = 2.998 x 10m/s. Attach a Screenshot of 700 nm Measurement from the Simulation to Lab Report Am G" nisinin c/noc) 700 500 400 Question . From data 2 = 700 nm in air, find the wavelength, and speed , in 2 medium. • Calculate frequency in air and glass for às = 700 nm. • When the incident is changed, what quantities will change in 2 medium? Data Table 2 Total Internal Reflection Set 2. = 650 nm (this is default value). Adjust Top Material (Medium 1) to glass= 1.500 and Bottom Material (Medium 2) to airn - 1.000. Press Red Button to produce light and set incident angle: - 30°. Measure refracted angle (*) Drag Intensity sensor out of Toolbox to measure relative Intensity of reflected ray(top) as hand retracted ray(bottom) as la. Calculate Bac by Snel's law cisind) (kop 4 significant figure) Attach a Screenshot of 41.8 Measurement from the Simulation to Lab Report 8: 02 Bac (4.1) 30 40 41.8 Question • Based on your data, what is your comment for > 41.8°? Calculate the critical angle (4 st.) of total internal reflection by Snell's law.

Answer 1

Part B Lab
Following is a screen shot of 700 nm Measurement from the simulation

Ray Wave 700 nm - Material Air - Index of Refraction (n) 1.000 45.0° 45.0° Air Water Glass 0 0 30 60 T - 30 - Material Glass - 28.2° Index of Refraction (n) 1.499 - Intensity Air Water Glass ? Speed Time Normal Angles Bending Light PHIET = Intro Prisms More Tools

Following is the completed data table from the given procedure in the lab manual

lambda1	theta2	n2m	n2=n1*sin(theta1)/sin(theta2)	c2' = c/n2
700	28.2	1.499	1.496361521	0.668288
500	28	1.499	1.506175959	0.663933
400	27.8	1.499	1.516138586	0.65957

Questions
1. lambda1 = 700 nm in air
lambda2 = lambda1/n2 = 700/1.5 = 466.66666666666 nm
speed in medium 2 is c/1.5 = 1.998666666*10^8 m/s
  
2.
now, v2 = v1 ( frequency does not change )
hence,
v2 = c/lambda1 = 4.2828571*10^14 Hz = v1
  
3. when lambda1 is changed, lambda2 changes, as well as theta 2 changes (because refractive index of a medium is actually dependent on the wavelength of the light being used)

Data table 2
The screen shot for theta = 41.8 deg measurement is as under

Ray O O Wave 650 nm Material Custom Index of Refraction (n) 1.500 41.8° 41.89 Air Water Glass 0 30 60 60 man 30 Material Custom A 87.7° - Index of Refraction (n) 1.000 - Air Water Glass é ? Speed - Time 86.87% Intensity Normal Angles 4 a Bending Light PHIET E Intro Prisms More Tools

The completed data table according to the manual is as under

theta1	theta2	I1	I2	theta2c
30	48.5	10.55	89.45	48.59038
40	74.5	38.8	61.2	74.61857
41.8	87.2	83.81	16.19	88.85036
42	-	100	0

Questions
1. fvor theta1 > 41.8 deg, total internal reflection happens and the beam gets totally reflected and there is no refraction of light
2. by snells law
critical angle be a
then
sin(a)/sin(90) = 1/1.5
a = arcsin(0.66667)
a = 41.8103 deg

C. Discovery
On changing the refractive medium, the refractive index changes
increasing refractive index for constant wavelength increases the angle of refraction and the critical angle as well

On selecting the wave form of rays, we can see that the reflectred and the refracted beam are out of phases to each other when ligh is going from opitically rarer medium to optically denser medium
where as when it moves from optically denser medium to optically ratrer medium the refracted and the reflected rays are in phase