Ne W2
1 0 KI. Calculate the luminous inten
Uislunce of the
luminous intensity and the
[HSEB 20651
U
total luminous flux from the sun
Solution:
Here, illuminance (I) = 1.5 x 10° lumen/m²,
Distance (T) = 1.5 x 10 km =1.5 x 108 m
Let L be the luminous intensity of the sun, then
or, L= TXT =1.5 x 10°x (1.5 x 108)2
= 3.375 x 102 cd.
Total luminous flux from the sun = 410 I
= 41 x 3.375 x 1021 = 4.24 x 1022 /m
Example 3. If a source has luminous intensity of 400 cd, (a) how much
luminous flux is emitted by the source? (b) what is the illuminance at a point
on the table which is 1.6 m directly below the source?
Solution:
Here, Luminous intensity (L) = 400 cd

3.82746e+26 watts

Explanation:

There are two ways to solve this problem. One way is to use the equation

L = 4πσR²T⁴

where

L = the sun's bolometric (all-spectrum) luminous power

σ = 5.670374419e-8 W m⁻² K⁻⁴ = the Stefan-Boltzmann constant

R = 6.957e+8 meters = the sun's radius

T = 5771.8 K = the sun's effective temperature

You find that

L = 3.82746e+26 watts

The other way to solve the problem is to use the Planck integral for radiant flux.

L = 4π²R ∫(v₁,v₂) 2hv³/{c² exp[hv/(kT)]−1} dv

where

h = 6.62607015e-34 J sec

c = 299792458 m sec⁻¹

k = 1.380649e-23 J K⁻¹

v₁ = 0 = frequency band lower bound, in Hz

v₂ = ∞ = frequency band upper bound, in Hz

You find, once again, that

L = 3.82746e+26 watts

The advantage of using the Planck integral becomes clear when you want to calculate the sun's luminous power only in a specific band, rather than across the entire spectrum. For example, if we do the calculation again, except that we use

v₁ = 4.1e+14 = frequency band lower bound, in Hz

v₂ = 7.7e+14 Hz = frequency band upper bound, in Hz

restricting ourselves to the visible spectrum. We find that

L (visible) = 1.56799e+26 watts

So the fraction of the sun's luminosity that is in the visible spectrum is

L (visible) / L = 0.4096686

i guess that visual aids present persuasive examples to what you are presenting, some factors would be theme (does it fit with the color, information, what you are presenting), size (can you see it, is it a big enough span of data/information), and overall look of the visual aid.

hope this : )

the answer would be c