Cracking the SAT Physics Subject Test

Although we’re dealing with two mediums now, remember that Rule #1 still applies while the wave is in the first medium (speed do ...

2 has a greater linear mass density than rope #1, and because v is inversely proportional to the square root of the linear mass ...

SUPERPOSITION OF WAVES When two or more waves meet, the displacement at any point of the medium is equal to the sum of the displ ...

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If the two waves have displacements of the same sign when they overlap, the combined wave will have a displacement of greater ma ...

STANDING WAVES When our prototype traveling wave on a string strikes the wall, the wave will reflect and travel back toward us. ...

Nodes and antinodes always alternate, they’re equally spaced, and the distance between two successive nodes (or antinodes) is eq ...

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For the first standing wave, notice that L is equal to 1( λ). For the second standing wave, L is equal to 2( λ), and for the thi ...

fn = Tip You can remember nodes as areas of “no displacement.” Antinodes are the opposite of that. These are the harmonic (or re ...

This shows that the length of the string is equal to 4( λ), so This is the fourth-harmonic standing wave, with wavelength λ 4 (b ...

Here’s How to Crack It The fundamental frequency for a standing wave is given by the equation f 1 = where v is the speed of a ...

SOUND WAVES Sound waves are produced by the vibration of an object, such as your vocal cords, a plucked string, or a jackhammer. ...

same direction. An important difference between sound waves and the waves we’ve been studying on stretched strings is that the m ...

Questions 10-11 A sound wave with a frequency of 343 Hz travels through the air. What is its wavelength? If its frequency incre ...

Intensity and Decibel Level How loud we perceive a sound depends on both frequency and amplitude. Given a fixed frequency, we ca ...

Decibel Level: β = 10 log( ) I 0 is the threshold of hearing and is equal to 10−12 watts. Note that, while β is measured in deci ...

If frequencies f 1 and f 2 match, then the combined waveform doesn’t waver in amplitude, and no beats are heard. For example, pi ...

RESONANCE FOR SOUND WAVES Just as standing waves can be set up on a vibrating string, standing sound waves can be established wi ...

Although sound waves in air are longitudinal, here we’ll show the wave as transverse so that it’s easier to determine the wavele ...