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The Photoelectric Effect

Author: Sarah Kenyon



Time: 1-2 class periods
Preparation
Time:
1 hour: Gathering materials (posterboard, paper, pens, glue, scissors, other craft materials)
Materials: Posterboard
Paper
Pens
Glue
Scissors
Computer access

 


Abstract
This Explain activity asks students to represent the photoelectric effect in a poster form and to make a physical or pictorial representation of how an imaging method (that uses EM radiation) works. Students will first receive instruction as to what the photoelectric effect is, and will then use this to create their poster. They are free to choose any EM-related method previously discussed in this learning cycle.


Objectives
Students will:
1. In small groups, create a visual (poster) description of:
a. the photoelectric effect
b. one imaging type that uses EM radiation and explain how it works

National Science Standards
Content Standard A: Scientific Inquiry
Identify questions that guide scientific inquiry
Content Standard B: Physical Science
Structure and properties of matter
Content Standard E: Science and Technology
Identify a problem or design an opportunity
Communicate the problem, process, and solution
Content Standard F: Science in personal and social perspectives
Personal and community health
Natural and human-induced hazards
Science & Technology in local, national and global challenges

Teacher Background
Teacher Background: EM, waves, Photoelectric effect supplement
In this activity, it is important that you give students an overview of the photoelectric effect: both its historical significance and what it means. The following sites would be good supplements to the teacher background sheet above: http://www.phys.unsw.edu.au/~jw/FAQ.html#photoelectric This activity could be used if you have the proper resources (supplied by the teacher or located at separate stations) http://www.walter-fendt.de/ph14e/photoeffect.htm

Resource Websites

http://www.phys.unsw.edu.au/~jw/FAQ.html#photoelectric
http://www.walter-fendt.de/ph14e/photoeffect.htm

 

 

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.

 

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.

 


PULSE is a project of the Community Outreach and Education Program of the Southwest Environmental Health Sciences Center and is funded by:


an
NIH/NCRR award #16260-01A1
The Community Outreach and Education Program is part of the Southwest Environmental Health Sciences Center: an NIEHS Award

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Supported by NIEHS grant # ES06694


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Last update: November 10, 2009
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