Index of Refraction
“There will always be something left to know, something to excite the imagination of the poet and those
attuned to the great world in which they live.” ― Robert Frost
Answer each of the following questions to the best of your ability.
For each question, clearly illustrate your solution path. Show all
work and use clear concise language to justify your thinking. Work
from observations and first principles, not memorization. When
possible, use sketches and diagrams to support your claims.
Use the solutions (if provided) to evaluate each answer. Revise
your work as needed, monitor and reflect on your thinking, and
make any necessary corrections.
Create a GRAPHIC, FOCUSED, and ORDERED science poster to
illustrate your answers to each question. Post your work to
Seesaw. Work done in Formative alone will not be assessed.
Use the PhET Bending Light simulation for support.
Observe and Find a Pattern
Fill a fish tank with water and shine the light from a laser pointer
at different angles on the top surface of the water. The angle θ1 of
the incident beam relative to the normal line and the angle of the
beam that propagates into the water (the so-called refracted ray
θ2 are shown in the diagram and recorded in the table. Various
trigonometric functions of those angles are recorded as well.
Use any or all of the values given in the table to devise a rule that
relates the angle of incidence and the angle of refraction. Hint:
You might see if the ratio of two quantities has the same value for
all angles. If so, use this to help devise a rule.
While performing the experiment, you see a dot of light on the
Observe and Find a Pattern
This time shine the light through air onto a block of glass with a
smooth surface. The table records the angle between the incident
light and the normal line and the angle between the refracted light
and the normal line.
Use the rule relating the angle of incidence and the angle of
refraction that you devised in the previous activity, only this time
apply it for light propagation from air into glass. Compare and
contrast the air–glass refraction with the air–water refraction.
Reason and Explain
Different colors of light have different indexes of refraction when
passing through water droplets as shown below:
How can this information qualitatively explain why we see a
rainbow while it rains? Think about where the Sun is located with
respect to an observer when the observer sees a rainbow. What
assumption about the shape of the water droplets in the air can we
Represent and Reason
The eyes of a person standing at the edge of a 1.2-m-deep
swimming pool are 1.6 m above the surface of the water. The
person sees a silver dollar at the bottom of the pool at a 37° angle
below the horizontal. Assume the water surface is smooth, and the
index of refraction of water is 1.33. Determine the horizontal
distance d from the person to the dollar. Create a labeled ray
diagram, represent mathematically, solve, and evaluate the