Star A has a temperature of 9000 K while Star B has a temperature 3000 K. If the two stars are the same size, according to the Stefan-Boltzmann law, how much brighter is star A than star B?

Star A is this many times (9000)^4 x [4 π R^2 σ]  brighter than Star B =  (3000)^4 x [4 π R^2 σ]

Explanation:

In accordance with the Stefan-Boltzmann Law,

L = 4 π R^2 σ Τ^4

(Where L = is the energy emitted out by star i.e., Brightness, R = Radius of the star, σ = 5.67 x 10^-8 Stefan-Boltzmann Constant and T is the temperature of the star)

Star A = (9000)^4 x [4 π R^2 σ]

Star B =  (3000)^4 x [4 π R^2 σ]

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer