A person stands directly in front of two speakers that are emitting the same pure tone. The person then moves to one side until no sound is heard. At that point, the person is 7.15 m from one of the speakers and 7.18 m from the other. What is the frequency (in Hz) of the tone being emitted?
Properties of sound
A sound wave is a mechanical wave (or mechanical vibration) that transit through media such as gas (air), liquid (water), and solid (wood).
Quality Of Sound
A sound or a sound wave is defined as the energy produced due to the vibrations of particles in a medium. When any medium produces a disturbance or vibrations, it causes a movement in the air particles which produces sound waves. Molecules in the air vibrate about a certain average position and create compressions and rarefactions. This is called pitch which is defined as the frequency of sound. The frequency is defined as the number of oscillations in pressure per second.
Categories of Sound Wave
People perceive sound in different ways, like a medico student takes sound as vibration produced by objects reaching the human eardrum. A physicist perceives sound as vibration produced by an object, which produces disturbances in nearby air molecules that travel further. Both of them describe it as vibration generated by an object, the difference is one talks about how it is received and other deals with how it travels and propagates across various mediums.
A person stands directly in front of two speakers that are emitting the same pure tone. The person then moves to one side until no sound is heard. At that point, the person is 7.15 m from one of the speakers and 7.18 m from the other. What is the frequency (in Hz) of the tone being emitted? (Assume air temperature to be 20°C.)
According to the question, a person stands directly in front of two speakers that are emitting the same pure tone. The person then moves to one side until no sound is heard. At that point, the person is 7.15 m(=) from one of the speakers and 7.18 m() from the other.
Since, no sound is heard so there is a destructive interference of the sound waves coming from both the speaker.
Thus,
Path difference=
i.e.,
We know, phase velocity is given by:
where,
n is the frequency
is the wave length
V=speed of sound in air=330 m/s
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