IB AHL Topic 9 Interference Lessons

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AHL Topic 9 - Lessons 4 & 5: Interference Textbook References: Hamper IB HL Physics 2nd Edition p ; Oxford Text pp Understandings:

Young’s double-slit experiment

Modulation of two-slit interference pattern by one-slit diffraction effect

Multiple slit and diffraction grating interference patterns

Applications and skills:

Qualitatively describing two-slit interference patterns, including modulation by one-slit diffraction effect

Investigating Young’s double-slit experimentally

Sketching and interpreting intensity graphs of double-slit interference patterns

Solving problems involving the diffraction grating equation

Main Activities: Task #1: Watch this Video on Thomas Young's Double Slit Experiment (8 min) Task#2: Explore factors that effect the spacing (or angular separation) and width of the bright interference fringes by changing: a) wavelength of light b) slit separation distance c) distance of double slits from the screen using this Simulation of the Double Slit Experiment. Record your findings in your notebook. (12 mins).

Task#3: Click on this link to view a Simulation of Multiple Slit Interference Patterns. (You will need to follow the prompt to download the free Wolfram CDF Player & install it to be able to interact with the simulation.)

Write into your notebook your observations o the effect of using multiple slits and how the interference patterns changes as the number of slits is increased.(10 mins)

Task #4: Download and go through this Powerpoint on Diffraction and Interference carefully. (15 mins)

Task #5: Download and complete these two worksheets: (i) Worksheet 1 Interference of Two sources (ii) Worksheet 2 Single Slit Diffraction and Young's Double Slit Experiment (35 mins) Task #6: Use these Answer Sheets to check your answers to Worksheets 1 and 2 (20 mins)