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A sound wave is diffracted as it passes through a doorway but a light wave is not - Leaving Cert Physics - Question 4(d) - 2006
Question 4(d)
A sound wave is diffracted as it passes through a doorway but a light wave is not. Explain why.
Worked Solution & Example Answer:A sound wave is diffracted as it passes through a doorway but a light wave is not - Leaving Cert Physics - Question 4(d) - 2006
Step 1
Wavelength of Light vs Sound
Answer
The primary reason that sound waves diffract through a doorway whereas light waves do not is related to their wavelengths. The wavelength of sound is significantly longer than that of light. For instance, sound waves in air have wavelengths on the order of meters, while visible light has wavelengths in the nanometer range (about 400 to 700 nm). This difference in wavelength is crucial in understanding diffraction.
Step 2
Effect of Doorway Size
Answer
When a wave encounters an opening (like a doorway), diffraction occurs if the wavelength of the wave is comparable to the size of the opening. Since the wavelength of sound is much longer, it can bend around the edges of the doorway, spreading out into the space beyond. In contrast, the much shorter wavelength of light does not experience significant diffraction when passing through a doorway of typical size, resulting in minimal spreading.
Step 3