Echo

Sound waves can be reflected by large, hard surfaces like buildings, walls and cliffs. Reflection of sound occurs just like the reflection of light.     Echo is a distinct, reflected sound wave from a surface. A reflected sound can be heard separately from the original sound if the sound source is closer to the receiver while the reflecting hard …

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Range of Audible Frequencies

The human ear responds to sounds with frequencies in the range from 20 Hz to 20,000 Hz. This is called the audible range of the human ear. Examples of vibrating sources that produce sound in the audible range of frequencies are drums, guitar strings, tuning fork, human vocal cords and diaphragms of loudspeakers. In audible sound waves whose frequencies are …

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Propagation Of Sound Waves

Vibration in the tuning fork produces disturbances in the surrounding air. When the prongs’ movement is outwards, the prongs push the surrounding air molecules away, creating a local compression. This disturbance of air layers is then passed from molecule to molecule by collisions, causing the local compression to move outwardly. When the prongs’ movement is inwards, a partial void, or …

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Production Of Sound

Sound is a mechanical wave phenomenon and is normally associated with our sense of hearing. Sound is a property of vibrating objects. Sound is produced by vibrating sources in a material medium. Medium can be any gas, liquid or solid. The vibrating sources set the particles of a medium in vibration in such a way that sound travels outwards in …

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Sound

This topic covers “Sound” of O Level Physics. (Equivalent to American high school diploma) Sub-topics: Production of sound Propagation Of Sound Waves Range of audible frequencies Determining speed of sound in air Loudness and pitch Echo Ultrasound Quiz: Click here for quiz.

Minimum Thermometer

It measures the minimum temperature in a day. Alcohol is used as thermometric liquid. There is a steel index inserted inside the capillary tube. Spring connected to the index prevents it from moving forward freely. With decreasing temperature, alcohol contracts and pulls the steel index along the capillary tube. The index will be left at the lowest position to which …

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Maximum Thermometer

It measures the maximum temperature in a day. Mercury is used as thermometric liquid. There is a steel index inserted inside the capillary tube. Spring connected to the index prevents it from moving back to the bulb. With increasing temperature, mercury expands and pushes the steel index along the capillary tube. The index will be left at the furthest position …

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