Activity
1) Collect the Detection Detective activity sheets
from the students.
2) Review with the students the details of the photoelectric
effect. Students should understand that the wavelength
or frequency of a photon represents its energy, while
the amplitude determines how many photons are delivered
at a given point in time. When this energy hits a certain
level, it can interact with a given material to release
electrons. This is based on the matching of the energy
needed to remove the electron with that of the incident
photon. Einstein discovered the photoelectric effect;
that incident light, when hitting a metal plate, would
result in the release of electrons. These released
electrons could be measured as an electric current.
This was explained
in Einstein’s Nobel Prize winning paper in 1905,
and relied upon Plank’s description of light as
quantized packets of energy. You may do this via a lecture
or through brief readings.
3) Either individually or as a class, have students
use the java applet: http://www.walter-fendt.de/ph14e/photoeffect.htm to explore the photoelectric effect.
4)
If individual computers are available (or a computer
that can be visited during steps 5 and 6, students
should individually calculate Planck’s constant
from the applet.
5) In small groups, have them create a poster that
offers a visual description of the photoelectric
effect. It
must be clear enough to educate someone who has
not previously encountered it Materials to create
these
posters will
be provided in the classroom.
6) Students must include:
a. A clear description of how wavelength changes
result in differences in photon energy
b. A clear description of how amplitude changes
result in photon quantity changes (plus incorporate
the
idea of intensity)
c. A description of how the effect is measured
d. Describe how EM radiation affects atoms/matter
(i.e. http://hyperphysics.phy-astr.gsu.edu/hbase/mod3.html)-
they will have encountered this at the teacher
station in the previous lesson) and what general
energies
they
would expect to exhibit a photoelectric effect
and why.
e. Choose one imaging technique and visually
describe how it works.
7) The teacher should make circuits of the
classroom, asking questions to assess student
understanding
and evaluate group dynamics.
Closure
Ask students
to answer the following question in their notebook “How
does the nature of the material change the impact of an incident
EM ray?” If time allows, have the students discuss this
among themselves after answering.
Homework
None.
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Embedded
Assessment
Students
can be assessed on the thoroughness of their poster,
as well as its clarity. At the very least, it must be
clear that the student group understands the principles,
no matter how clearly they can portray it. The teacher
should go around and evaluate each poster by posing questions
to the students and having them explain the different
parts of their poster. Depending on the class (higher
level or integrated) more emphasis can be put on the
effective presentation of information vs. correct presentations.
Students can be individually evaluated (if they’re
able to do the applet individually) on whether they get
correct answers for Planck’s constant.
Students’ ability to work in groups and synthesize
provided material into an organized unit can also be
assessed.
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