For each squre metre of the sun\'s visible surface the rate of energy transferre
ID: 1483432 • Letter: F
Question
For each squre metre of the sun's visible surface the rate of energy transferred to outer space is 63 MW. The emissivity of the sun's surface is approximatel 1.0. Which of the following statements is correct?
a) The temperature of the sun's surface is approximately 5766 K.
b) The solar energy that reaches the earth from the sun involves radiative heat transfer primarily.
c) Because the sun's surface temperature is relatively stable it must be receiving energy from space at a rate of 63 MW/ m^2.
d) The energy transferred from the sun is carried mainly by the solar wind, so the process is primarily convective.
e) The rate at which energy leaves the surface if the sun cannot be calculated using the Stefan-Boltzmann law, because the sun's surface is white, not black
Explanation / Answer
A and D are correct.
From Stefan-Boltzmann Law, we can find the temperature of sun.
T= (E/(e*sigma))^(1/4) sigma= 5.67*10-8 e=1(given) E= rate of energy transferred
Applying this formula will give us approx. 5766 K.
Also, In the Sun's outer layer, from its surface to approximately 200,000 km below
,the temperature is lower than in the radiative zone and heavier atoms are not
fully ionized. As a result, radiative heat transport is less effective.
The density of the plasma is low enough to allow convective currents to develop.
Material heated at the tachocline picks up heat and expands, thereby reducing its
density and allowing it to rise. As a result, thermal convection develops
as thermal cells carry the majority of the heat outward to the Sun's photosphere
and this is mostly in the form of solar wind.
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