Loading document…
Opening in Pages for Mac...
Your browser isn’t fully supported.
For the best Pages for iCloud experience, use a supported browser.
Learn More
Cancel
Continue
4.4 Wave behaviour
4. Oscillations and waves
Verifying Snell’s law
Background
“
Refraction of light at the interface between two media of different refractive indices, with n
2
> n
1
.
Since the velocity is lower in the second medium (v
2
< v
1
), the angle of refraction θ2 is less than
the angle of incidence θ
1
; that is, the ray in the higher-index medium is closer to the normal.
Snell's law
is a formula used to describe the relationship between the angles of incidence and
refraction, when referring to light or other waves passing through a boundary between two
different isotropic media, such as water, glass, or air.
”
Background
:
https://en.wikipedia.org/wiki/Snell%27s_law
Experiment
: how does the angle of incidence affect the angle of refraction?
Equipment
: rectangular prism, ray box, fringe, protractor, ruler, pencil or phet
Method
1.
Draw around a rectangular prism and then shine a ray of light at a specifi c point where a
normal is drawn, placing two crosses at either end of the incoming ray and outgoing ray..
2.
Using a ruler, draw the lines for the ray of light, including while going through the prism.
3.
Measure the angle from the normal to the incoming ray (θ
1
) and the normal to the ray going
through the prism.
4.
Repeat at different angles to complete the table, calculating the sine of the values.
Data table
Analysis
Plot the graph of sin I against sin r. Using the graph, calculate n
2
/n
1
n
2
/n
1
is also equal to v
1
/v
2
. What is the wave speed in terms of c in glass? Show your working.
What is the wave speed in glass in m s
-1
? Show your working.
Angle of incidence, θ
1
/
o
Angle of refraction, θ
2
/
o
Sin θ
1
Sin
θ
2
10
0.174
20
0.342
30
0.500
40
0.643
50
0.766
60
0.866
70
0.940
80
0.985
4. Oscillations and waves
4.4 Wave behaviour
