Question

Use the inverse square law for light to answer each of the following questions. Part A Suppose a star has the same luminosity as our Sun (3.8×1026watts) but is located at a distance of 10 light−years . What is its apparent brightness?

Answer 1

Answer

The apparent brightness by inverse square law is $3.25*10^-^9watt/m^2$

Explanation:

b = L / ( 4 pi d^2 )

b = apparent brightness of the star (in watts/meter2)

L = luminosity of the star (in watts)

d = distance to the star (in meter)

pi = approximately 3.14159265

$Given\\d=10 light years=9.461*10^1^6\\L=3.8*10^2^6watts$

put all values in formula

$b=(3.8*10^2^6)/4*3.14*(9.641*10^1^6)^2$

$b=3.25*10^-^9watts/m^2$