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2 years ago

How do noise canceling headphones work?

Physics

2 answers:

postnew [5]2 years ago

5 0

Answer:

B.) by interfering with sound waves

Explanation:

As we know that the interference of sound waves is of two types

1). constructive interference

2). destructive interference

now we know that constructive interference means the resultant intensity will be more than the intensity of interfering waves as here two waves are in same phase.

In destructive interference the resultant of two waves is given by the minimum resultant of the intensity as here the phase of two waves are opposite to each other.

So we will say that

$I = \sqrt{(I_1 + I_2 + 2\sqrt{I_1I_2}cos\theta)}$

here in case of noise cancelling headphones we know that the phase of noise is always made in opposite phase with the sound which is used to cancelled the noise.

This will reduce the noise and we will get a clear sound

Aloiza [94]2 years ago

4 0

Answer:

B.) by interfering with sound waves

Explanation:

im right hashsjashj add the gram bc the main got deleted :(

que.quieres15 <follow that

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DedPeter [7]

I believe the answer is A.

4 0

2 years ago

Read 2 more answers

Two concrete spans of a 380 m long bridge are

Mazyrski [523]

Answer:

4.163 m

Explanation:

Since the length of the bridge is

L = 380 m

And the bridge consists of 2 spans, the initial length of each span is

$L_i = \frac{L}{2}=\frac{380}{2}=190 m$

Due to the increase in temperature, the length of each span increases according to:

$L_f = L_i(1+ \alpha \Delta T)$

where

$L_i = 190 m$ is the initial length of one span

$\alpha =1.2\cdot 10^{-5} ^{\circ}C^{-1}$ is the temperature coefficient of thermal expansion

$\Delta T=20^{\circ}C$ is the increase in temperature

Substituting,

$L_f=(190)(1+(1.2\cdot 10^{-5})(20))=190.0456 m$

By using Pythagorean's theorem, we can find by how much the height of each span rises due to this thermal expansion (in fact, the new length corresponds to the hypothenuse of a right triangle, in which the base is the original length of the spand, and the rise in heigth is the other side); so we find:

$h=\sqrt{L_f^2-L_i^2}=\sqrt{(190.0456)^2-(190)^2}=4.163 m$