Question 18M.3.SL.TZ1.b.ii

$\frac{L_{\text{X}}}{L_{\text{s}}}=\frac{R_{\text{X}}^2\times {\text{T}}_{\text{X}}^4}{R_{\text{s}}^2\times {\text{T}}_{\text{s}}^4}$

OR

$R_{\text{X}}=\sqrt{\frac{L_{\text{X}}{\text{T}}_{\text{s}}^4}{L_s{\text{T}}_{\text{X}}^4}}\times R_{\text{s}}$

$R_{\text{X}}=\sqrt{\frac{35\times {6000}^4}{10{000}^4}}\times R_{\text{s}}$ (mark for correct substitution)

R_X = 2.1R_s

Allow ECF from (b)(i).

Accept values in the range: 2.0 to 2.3R_s.

Allow TS in the range: 5500 K to 6500 K.

[3 marks]