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Svetlanka [38]
3 years ago
9

Assume (unrealistically) that a TV station acts as a point source broadcasting isotropically at 3.2 MW. What is the intensity of

the transmitted signal reaching Proxima Centauri, the star nearest our solar system, 4.3 ly away? (An alien civilization at that distance might be able to watch X Files.) A light-year (ly) is the distance light travels in one year._______W/m2
Physics
1 answer:
Dahasolnce [82]3 years ago
4 0

Answer:

I=1.5\times10^{-28}W/m^2

Explanation:

The intensity is related to the power and surface area by I=\frac{P}{A}=\frac{P}{4\pi r^2}. We need to calculate the surface area of a sphere of radius r=4.3ly.

Since 4.3ly is the distance light travels in 4.3 years at 299792458m/s, we can obtain it in meters by doing:

r=vt=(299792458m/s)(4.3\times365\times24\times60\times60s)=4.1\times10^{16}m

So we have:

I=\frac{P}{4\pi r^2}=\frac{3.2\times10^6W}{4\pi (4.1\times10^{16}m)^2}=1.5\times10^{-28}W/m^2

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Points A, B, and C are at the corners of an equilateral triangle of side 8 m. Equal positive charges of 4 mu or micro CC are at
aliina [53]

Answer:

a) 8.99*10³ V  b) 4.5*10⁻² J c) 0 d) 0

Explanation:

a)

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        V =\frac{k*q}{d}

  • As the electrostatic force is linear with the charge (it is raised to first power), we can apply superposition principle.
  • This means that the total potential at a given point, is just the sum of the individual potentials due to the different charges, as if the others were not there.
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        V = \frac{2*q*k}{d} = \frac{2*8.99e9N*m2/C2*4e-6C}{8m} =\\ \\ V= 8.99e3 V

  • The potential at point C is 8.99*10³ V

b)

  • The work required to bring a positive charge of 5μC from infinity to the point C, is just the product of the potential at this point times the charge, as follows:

        W = V * q = 8.99e3 V* 5e-6C = 4.5e-2 J

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c)

  • If we replace one of the charges creating the potential at the point  C, by one of the same magnitude, but opposite sign, we will have the following equation:

       V = \frac{8.99e9N*m2/C2*(4e-6C)}{8m}  + (\frac{8.99e9N*m2/C2*(-4e-6C)}{8m}) = 0

  • This means that the potential due to both charges is 0, at point C.

d)

  • If the potential at point C is 0, assuming that at infinity V=0 also, we conclude that there is no work required to bring the charge of 5μC from infinity to the point C, as no potential difference exists between both points.
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What type of medium (solids, liquids, or gases) do sound waves travel fastest in?
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Answer:

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Explanation:

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Create your own simple metaphor illustrating how demand and supply work together to create equilibrium. Label the following on y
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''When the quantity demanded intersect with quantity supplied, it leads o the formation of equilibrium point.''

<h3>How equilibrium occur?</h3>

The equilibrium price and equilibrium quantity occur where the supply and demand curves cross with each other. The equilibrium occurs when the quantity demanded is equal to the quantity supplied.

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A grandfather paradox is a situation where individual travels to the past and then introduces a change which affects or contradicts the present.

<h3>What is a grandfather paradox?</h3>

A paradox is a situation or statement which involves two contradictions.

A grandfather paradox is a situation which is defined by the ability of an individual to travel to a time in the past usually before the birth of their grandfather and then introduces a change which affects or contradicts the present. For example, killing the grandfather to prevent their birth.

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