Home Browse Tutorials Instructor Resources Research Events About
Tutorials in Introductory Physics » Dynamics first » Wave properties of light
Edition 1st

Wave properties of light

Variant i Dynamics first   Other Variants Interactive tutorial lecture      

Students develop an analogy between two-source interference in the context of water and double-slit interference in the context of light. The homework introduces intensity graphs.

Topics   Waves and optics / Physical optics: models, representations, periodic circular waves, wave front diagrams, and physical optics

Jump to:

Materials

Materials by the UW team

  • Group HandoutTiIP_Dyn1st_1stEd_WPL_handouts.pdfVerification required
  • Instructor GuideTiIP_Dyn1st_1stEd_WPL_instructor-guide.pdfVerification required
  • PretestTiIP_Dyn1st_1stEd_WPL_pretest.pdfVerification required
  • Exam QuestionsTiIP_Dyn1st_1stEd_WPL_exam.pdfVerification required
  • Equipment ListTiIP_Dyn1st_1stEd_WPL_equipment.pdf


Group Handout
Handouts to be printed and one distributed to each group of students to supplement worksheet

Verification requiredLogin or register to see a preview and download

Tutorial details

The tutorial begins by having students make observations of water waves passing through slits of various widths. They come to recognize that when a slit is sufficiently narrow, it results in waves that are nearly those from a point source and that when the slit is sufficiently wide it does not significantly affect the shape of the wavefronts. Students are led to realize that they can apply ideas developed in the preceding tutorial, Two-source interference, to the case of water waves incident on two very narrow slits.

In the next section of the tutorial, students consider a double-slit interference pattern from light. They recognize that the pattern is different from that predicted by geometrical optics. Students compare this situation to that of periodic water waves incident on two very narrow slits. They are guided to make an analogy between water waves and light. They are led to recognize that if one of the slits were covered, the screen would be (essentially) uniformly bright; there would be no points of zero intensity.

The students then make predictions about how a variety of changes (e.g., decreasing the distance between the slits or moving the screen closer to the mask) would affect the interference pattern. The final problem is quantitative.

Note: The tutorial makes the approximation that the slits are sufficiently narrow that they may be treated as point sources of light. (In the tutorial Diffraction students consider how the width of the slit affects the diffraction pattern.)

For instruction tips, login or register as a verified educator to see the Instructor Guide.

Prerequisites

Prerequisite tutorials

The Two-source interference tutorial is a prerequisite to Wave properties of light.

Other prerequisites

Students should have worked through the tutorial Two-source interference and the related homework.

Equipment

Special Instructions

buckets of water

paper towels (for clean up)

  • 1 beaker or plastic container (to transfer water from buckets to pans)
  • 6 aluminum baking pans to serve as ripple tanks
  • 12 small blocks or pieces of sponge, (to form slits of adjustable width in pans of water)
  • 6 wooden dowels, ~8” long and 1/2” diameter

Handouts:

  • 6 copies (each in a plastic protector) of photographs from tutorial (See Handouts.)

List

  • paper towels
  • water
  • white board or large sheet of paper with markers

Discussion

Coming Soon! We hope to release the discussion section on each tutorial soon.