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2 years ago

Through which medium is it impossible to transmit sound waves?.

Physics

1 answer:

dusya [7]2 years ago

4 0

Answer: vacuum

Explanation: The vacuum is the medium from where the sound wave cannot pass. A vacuum is basically an area without any air. Since the sound wave is a mechanical wave that's why it cannot travel through a medium where there is no matter of vibrations to works in, i.e, it can't travel through a vacuum.

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A wooden block meauring 40cm x 10cm x 5cm has a mass 850gm . find the density of wood?

Lelechka [254]

Answer:

Explanation:

Density = Mass / Volume = 850 / 40*10*5 = 0.425 g /cm^3

5 0

2 years ago

A 300 MHz electromagnetic wave in air (medium 1) is normally incident on the planar boundary of a lossless dielectric medium wit

Masja [62]

Answer:

Wavelength of the incident wave in air = 1 m

Wavelength of the incident wave in medium 2 = 0.33 m

Intrinsic impedance of media 1 = 377 ohms

Intrinsic impedance of media 2 = 125.68 ohms

Check the explanation section for a better understanding

Explanation:

a) Wavelength of the incident wave in air

The frequency of the electromagnetic wave in air, f = 300 MHz = 3 * 10⁸ Hz

Speed of light in air, c = 3 * 10⁸ Hz

Wavelength of the incident wave in air:

$\lambda_{air} = \frac{c}{f} \\\lambda_{air} = \frac{3 * 10^{8} }{3 * 10^{8}} \\\lambda_{air} = 1 m$

Wavelength of the incident wave in medium 2

The refractive index of air in the lossless dielectric medium:

$n = \sqrt{\epsilon_{r} } \\n = \sqrt{9 }\\n =3$

$\lambda_{2} = \frac{c}{nf}\\\lambda_{2} = \frac{3 * 10^{6} }{3 * 3 * 10^{6}}\\\lambda_{2} = 1/3\\\lambda_{2} = 0.33 m$

b) Intrinsic impedances of media 1 and media 2

The intrinsic impedance of media 1 is given as:

$n_1 = \sqrt{\frac{\mu_0}{\epsilon_{0} } }$

Permeability of free space, $\mu_{0} = 4 \pi * 10^{-7} H/m$

Permittivity for air, $\epsilon_{0} = 8.84 * 10^{-12} F/m$

$n_1 = \sqrt{\frac{4\pi * 10^{-7} }{8.84 * 10^{-12} } }$

$n_1 = 377 \Omega$

The intrinsic impedance of media 2 is given as:

$n_2 = \sqrt{\frac{\mu_r \mu_0}{\epsilon_r \epsilon_{0} } }$

Permeability of free space, $\mu_{0} = 4 \pi * 10^{-7} H/m$

Permittivity for air, $\epsilon_{0} = 8.84 * 10^{-12} F/m$

ϵr = 9

$n_2 = \sqrt{\frac{4\pi * 10^{-7} *1 }{8.84 * 10^{-12} *9 } }$

$n_2 = 125.68 \Omega$

c) The reflection coefficient,r and the transmission coefficient,t at the boundary.

Reflection coefficient, $r = \frac{n - n_{0} }{n + n_{0} }$

You didn't put the refractive index at the boundary in the question, you can substitute it into the formula above to find it.

$r = \frac{3 - n_{0} }{3 + n_{0} }$

Transmission coefficient at the boundary, t = r -1

d) The amplitude of the incident electric field is $E_{0} = 10 V/m$

Maximum amplitudes in the total field is given by:

$E = tE_{0}$ and $E = r E_{0}$

E = 10r, E = 10t

3 0

2 years ago

According to Coulomb's law, the electrical force between two charged objects:A.is zero if they are opposite charges.B.increases

kondor19780726 [428]

Answer and explanation:

A correct option is an option (B).

The electrical force between two charges is given as,

$F=\frac{1}{4\pi\epsilon_0}\frac{q_1q_1}{r^2}$

The electrical force is directly proportional to the product of two charges. Thus Force will depend on two charges irrespective of their signs.

Option (A) is incorrect because if charges are opposite, the value of force will not be zero. It will be -ve.

Option (C) is incorrect because the force is directly proportional to the product of charges, it depends on the amount of charge.

Option (D) is also incorrect because the force in inversly proportional to the distance between two charges. Thus, if the distance between two charges is increased, the force between two charges will decrease.

Concllusion:

The correct option is option (B).

7 0

6 months ago

1. What conditions are necessary for a hurricane to form?

tekilochka [14]

Each year is a different anount of hurricanes but on the Pacific Ocean there is about 14 hurricanes (that's form). Hurricanes rotate clockwise. The Saffir-Simpson scale, it's measured on a scale 1-5 property damage and flooding along the coast. Hurricanes get their names from meteorologist a long time ago from their communication about them being more effectively and to tell whether to stay more farther away from the hurricane. The calmest winds in the hurricane is the, Eye. Which the Eye is also called the, cyclone. The strongest winds are in the right-front side of the hurricanes center. Hope this helped! Sorry that I couldn't get everything.

7 0

2 years ago

Light from the star Betelgeuse takes 640 years to reach Earth. How far away is Betelgeuse in units of light-years? Name any hist

Eduardwww [97]

Answer:

Betelgeuse is 640 light years away from earth.

Explanation:

A light-year is an astronomical unit to measure the distance the light travels in a calendar year.

If the light from a star takes 640 years to reach us, then that star its 640ly away from us.

Betelgeuse has been labeled as a Variant Star, which means that its brightness can fluctuate over the course of years, this has made difficult for astronomers to measure the exact distance of the star. Right now the star is estimated to be around 613 and 881ly away from earth, although, for the sake of your second question, we will take 640 years as our estimated value.

In 1380 (640 years ago) the Battle of Kulikovo took place. A battle of remarkable importance to Russian history, in which the Russian army, led by Prince Dmitry of Moscow, defeated the Mongol army, defining a turning point in the Mongol dominance, and setting the bases for what Russia is today.

6 0

3 years ago

Read 2 more answers