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Lesson: Beat Frequencies Physics

In this lesson, we will learn how to relate the beat frequency produced by the superposition of two waves to the waves’ frequencies.

Lesson Plan

Students will be able to

recognize that two waveforms that interfere produce a resultant waveform that has a frequency different to either of the interfering waveforms,
relate two waveforms with similar frequencies to their resultant waveform graphically,
recognize that the frequencies of two interfering waveforms, and , are related to the frequency of their resultant waveform, , by the equation .

Lesson Worksheet

Q1:

Two sound waves produce a beat frequency of 2.4 Hz. The higher-frequency sound wave has a frequency of 1,025.8 Hz. What is the frequency of the other sound wave? Answer to five significant figures.

Q2:

What beat frequency is produced by two sound waves that have frequencies of 102 Hz and 97 Hz? Answer to one significant figure.

Q3:

When two waves that have slightly different frequencies are superposed, they produce a beat frequency. Which of the following formulas correctly relates the frequencies of the two waves, and , where , to the beat frequency, ?