PASCO OS-8515C Basic Optics System - Manual (Page 30)

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B a s i c O p t i c s S y s t e m E x p e r i m e n t 1 0 : R e v e r s i b i l i t y
30
Record Data
Trial 1
1. Turn the ray table so
the incoming ray
enters the lens
through the flat sur-
face (see Figure
10.2).
2. Rotate the ray table
to set the angle of
incidence to each of
the values listed in
the first column of
Table 10.1. For each
angle of incidence
(
θ
i1
), observe the
corresponding angle
of refraction (
θ
r1
)
and record it in the second column of the table.
Trial 2
1. Copy all of the values in the second column to the third column of the table. (In
other words, the angles of refraction that you observe in Trial 1 will be the angles
of incidence that you use in Trial 2.)
2. Turn the ray table so the incoming ray enters the lens through the curved surface.
3. For the angles of incidence (
θ
i2
) that you wrote in the third column of the table,
observe the corresponding angles of refraction (
θ
r2
) and record them in the fourth
column.
Analysis
1. Using your values for
θ
i1
and
θ
r1
and Snell’s Law (Equation 10.1), determine the
index of refraction of acrylic (n
acrylic
). Assume the index of refraction of air (n
air
)
is 1.0.
(eq. 10.1)
n
acrylic
= ___________ (from
θ
i1
and
θ
r1
)
2. Determine n
acrylic
again, this time using your values of
θ
i2
and
θ
r2
.
n
acrylic
= ___________ (from
θ
i2
and
θ
r2
)
Questions
1. Is the law of refraction the same for light rays going in either direction between
the two media?
2. Does the principle of optical reversibility hold for reflection as well as refraction?
Explain.
Table 10.1: Data
Trial 1
Ray Incident on Flat Surface
Trial 2
Ray Incident on Curved Surface
Angle of Incidence
θ
i1
Angle of Refraction
θ
r1
Angle of Incidence
θ
i2
Angle of Refraction
θ
r2
0°
10°
20°
30°
40°
50°
60°
70°
80°
n
air
θ
i1
( )
sin n
acrylic
θ
r1
( )
sin =