Sound

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Q. How we 'hear' sounds? A. When something makes a **noise**, it sends **vibrations**, or **sound waves**, through the **air**.

Q. How the ear drum works? A. The human eardrum is a **stretched membrane**, like the skin of a drum. When the sound waves hit your eardrum, it **vibrates** and the __brain interprets these vibrations as sound__.

Q. What is the speed of sound? A. In dry air at 20 °C, the speed of sound is **343 meters per second**. For different gases, the speed of sound is dependent on the mean molecular weight of the gas.

Q. What is the doppler effect? A. The doppler effect is the **change in frequency of a wave** for an observer moving relative to the source of the wave. It was named after Austrian physicist Christian Doppler who proposed it in 1842.

Q. What does wavelength mean? A. In Physics, the wavelength of a sinusoidal wave is the **spatial period of the wave**.

WAVELENGTH