Ruska Builds the First Electron Microscope (Grades 9-12+)

Ernst Ruska. (c) The Nobel Foundation.

As a student, Ernst Ruska experimented with the theory that electron currents, which have a shorter wavelength than light, could magnify images beyond the capabilities of the light microscope. On April 7, 1931 (at the ripe old age of 24), Ruska conducted the experiments that would earn him a Nobel Prize. He obtained experimental proof that, similar to using multiple lenses to magnify specimens in light optics, an object's image could be further magnified by using two short electromagnetic coils.

The resolving power of a light microscope is limited by the wavelength at which light travels (about 4,000 angstroms). The electron microscope uses an electron beam with a wavelength of less than 1 angstrom, which can magnify objects up to 1 million times. Some of the electrons pass through the specimen, and others bounce off it. The scattered electrons, focused by a pair of electromagnets that form the "lens" of the microscope, produce a visible image on a fluorescent screen or photographic film.

Connections

The dramatic images produced by electron microscopes can be used as a hook to engage students in exploring the physics of how they work. Start by viewing familiar objects such as insects, microchips, or coins under the optics of the light microscope. Now ask students if they can identify these same objects when imaged under an electron microscope. Your classroom discussion might include a comparison of the wavelengths in which light and electrons travel, absorption and refraction, and scale.

Resources on the World Wide Web offer a variety of tutorials, virtual microscopes, and even the opportunity to collaborate on real research projects. Encourage your students to use these resources to design and conduct their own research studies. For example, Iowa State University (listed below) invites students to submit their samples to be imaged. Another site invites classrooms to operate an actual microscope from their web browser. Once the research is done, students can prepare an authentic research report that may be worthy of publication!

Web Resources

1. The Development of the Electron Microscope and of Early Electron Microscopy
   
   http://ernst.ruska.de/daten_e/library/documents/999.nobellecture/lecture.html
   Read the full text of Ernst Ruska's Nobel lecture that describes his childhood and education and tells how he invented the electron microscope. The illustrations include sketches from his notebook, sample electromicrographs, and photos of historic instruments.
   
   
2. Press Release of Royal Swedish Academy of Sciences, Oct. 15, 1986
   
   http://ernst.ruska.de/daten_e/nobelprize/background/background.html
   The press release from the Royal Swedish Academy of Science announcing the award of a Nobel Prize to Ernst Ruska for his "fundamental work in electron optics, and for the design of the first electron microscope."
   
   
3. Ernst Ruska Autobiography
   
   http://www.nobel.se/physics/laureates/1986/ruska-autobio.html
   This page offers a short autobiography as well as a photo of Ernst Ruska.
   
   
4. The First Electron Microscope
   
   http://www.salonhogar.com/ciencias/microscopio/temruska.htm
   Visit this site to see a photograph of Ruska's microscope.
   
   
5. Scanning Electron Microscope
   
   http://www.mos.org/sln/sem/intro.html
   The definitive SEM site for teachers, this site offers animations and slide shows about the microscope, as well as classroom activities, an image gallery, and links.
   
   
6. Project ExCEL
   
   http://www.mse.iastate.edu/excel/
   This NSF-funded project allows you and your students to operate a scanning electron microscope with a standard web browser like Internet Explorer. If you are interested in examining a specimen that your class submits, you'll find a list of questions to consider before contacting the WebSEM team to schedule a session. In the lesson plans section, there are ideas for using the SEM in science subjects such as physics and biology. You'll also find tutorials that explain the workings of electron microscopes at three instructional levels: elementary, secondary, and college.
   
   
7. Microangela
   
   http://www.pbrc.hawaii.edu/bemf/microangela/
   Visit this cleverly named site to view an impressive gallery of colorized images of insects, human cells, microorganisms, and more.
   
   
8. Microscopy for Children: A Bibliography
   
   http://www.msa.microscopy.com/ProjectMicro/PMBooks.html
   The Microscopy Society of America has a terrific bibliography of resources in print, video, CD-ROM, and online.
   
   
9. Molecular Expressions
   
   http://micro.magnet.fsu.edu/
   (An ENC Digital Dozen selection, ENC#009995) A photo gallery displays hundreds of examples of color micrographs of substances such as amino acids, hormones, DNA, fatty acids, ice cream, moon rocks, and superconductors.
   
   
10. Dennis Kunkel Microscopy, Inc.: Scientific Photography Through the Microscope
    
    http://www.denniskunkel.com
    (ENC#016731) This site, maintained by renowned microscopist Dennis Kunkel, showcases his work and provides resources for colleges, schools, or individuals who want to learn more about microscopy.
    
    
11. Nanoworld Image Gallery
    
    http://www.uq.edu.au/nanoworld/images_1.html
    (ENC#004110) What do the chemoreceptors on the leg of a blowfly look like? How about the lamellae of human bones or the ultrastructure of the mitochondrion? This site has hundreds of images of biological specimens.
    
    

Ready-to-Go Activities

1. The JavaScript SEM for Students
   
   http://www.denniskunkel.com/PublicHtml/JAVA-SEM/begin.html
   With this simulation developed by photomicrographer Dennis Kunkel, students load a specimen into the chamber, turn on the vacuum, and choose their magnification.
   
   
2. Virtual Scanning Electron Microscope
   
   http://micro.magnet.fsu.edu/primer/java/electronmicroscopy/magnify1/index.html
   This tutorial enables students to enhance their images by adjusting the focus, contrast, brightness, and magnification.
   
   
3. How the SEM Works
   
   http://www.mos.org/sln/SEM/works.html
   This tutorial takes visitors step by step through a slide show that demonstrates the workings of the scanning electron microscope.
   
   
4. Secret Worlds: The Universe Within
   
   http://microscopy.fsu.edu/optics/tutorials/java/powersof10/index.html
   Starting 10 million light-years away from the Milky Way, this Java applet moves in closer and closer to Earth, through cells and organelles, until it reaches subatomic particles. A very dramatic representation of scale!
   
   
5. The Virtual Electron Microscope
   
   http://school.discovery.com/lessonplans/activities/electronmicroscope/
   Designed for younger students, this activity provides a delightful introduction to the electron microscope. Students click and drag a variety of "specimens" into a simulated electron microscope. The teacher notes provide background information and ideas for discussion questions and extension activities.
   
   
6. Carolina Tips Online: Murder in the Science Lab?
   
   http://www.carolina.com/tips/murder/Murd.asp
   (ENC#012065) The online version of Carolina Biological's newsletter provides articles and classroom activities. This activity from the January 1996 issue uses microscopes to solve a simulated murder in the science lab.
   
   

Classroom Resources from the ENC Collection

1. Technology: the microscope, our window on the world
   Date: 1999 Grade(s): 5 - 9 Cost: Free ENC#: 017842
   This video explores how the microscope is revolutionizing everyday life, from health improvements to advancements in computer hardware. In addition to the two types of electron microscopes (scanning and tunneling), the video reports on the limitations of the electron microscope, and discusses future microscopes that use sound waves, high-voltage electrons, and electron clouds.
   (For more details see ENC Record)
   
   
   
2. Unlocking the secrets of life
   Date: 1996 Grade(s): 9 - 12 Cost: $149.00 ENC#: 017115
   This videotape uses video microscopy and state of the art computer animation to show how some important cellular activities occur at the molecular level. The program leads viewers on a visual tour of progressively smaller subjects, requiring stronger and stronger magnification as the tour proceeds.
   (For more details see ENC Record)
   
   
   

Teacher Resources from the ENC Collection

1. Scope it out: standards based microscope lessons for the middle school
   Date: 1996 Grade(s): 5 - 8 Cost: $5.00 ENC#: 007434
   This inexpensive booklet provides an introduction to the microscope and how it works. Included are 24 lesson plans, along with guidelines for safety and assessment.
   (For more details see ENC Record)
   
   
   

Search Strategies

Find more materials by searching Curriculum Resources on ENC Online using these terms: Electron microscopy, Electrons, Microscopes, or Microscopy.

Connections to Standards

Realizing that there are many ways to use this Classroom Calendar entry, we chose these standards because they relate to the entry, in full or in part. If you want to explore the standards further, please use the link(s) provided.

Connections to NSES
Content Standard A: Science as Inquiry: Abilities necessary to do inquiry (9-12)
Content Standard A: Science as Inquiry: Understanding about inquiry (9-12)
Content Standard B: Physical Science: Transfer of energy (5-8)
Content Standard B: Physical Science: Structure of atoms (9-12)
Content Standard B: Physical Science: Interactions of energy and matter (9-12)
Content Standard C: Life Science: The cell (9-12)
Content Standard E: Science and Technology: Abilities of technological design (9-12)
Content Standard E: Science and Technology: Understanding about science and technology (9-12)
Content Standard G: History and Nature of Science: Science as a human endeavor (9-12)
Content Standard G: History and Nature of Science: Nature of scientific knowledge (9-12)
Content Standard G: History and Nature of Science: Historical perspectives (9-12)