Waves, Sound and Light: Light Waves

Light Waves: Audio Guided Solution

Problem 25:

Noah Formula lives near the airport and frequently notices poor AM radio reception occurring as planes use the approach path which passes over his home. Having just finished the unit on light wave behavior, Noah now understands that the reception problem occurs because of radio wave signals reflecting off the planes and destructively interfering with waves which approach his antenna directly from the station. Noah’s favorite station – WFIZ – broadcasts at 1240 kHz and is located several miles from his home. Determine the five lowest heights above his home for which reflection off of planes will lead to destructive interference of this 1240 kHz signal. (Assume that the reflected waves do not undergo a phase change upon reflection off the plane.)

Audio Guided Solution

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  • Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
  • Identify the known and unknown quantities and record in an organized manner, often times they can be recorded on the diagram itself. Equate given values to the symbols used to represent the corresponding quantity (e.g., v = 3.00x108 m/s, λ = 554 nm, f = ???).
  • Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
  • Identify the appropriate formula(s) to use.
  • Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.

Read About It!

Get more information on the topic of Light Waves at The Physics Classroom Tutorial.

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