Question

The peak value of the electric field, in the light radiated by a point source of power P₁ , at a point, distant r₁ from the source, is E₀₁. The corresponding value, for a point source of power P₂ , at a point, distant r₂ from the source, is E₀₂. The ratio \((\frac{E_{01}}{E_{02}})\) equals

(1) \((\frac{P_1r^2_1}{P_2 r^2_2})^{1/2}\)

(2) \((\frac{P_2r^2_2}{P_1 r^2_1})^{1/2}\)

(3) \((\frac{P_1r^2_2}{P_2 r^2_1})^{1/2}\)

(4) \((\frac{P_1r^2_1}{P_2 r_2})^{1/2}\)

Answer 1

 (3) \((\frac{P_1r^2_2}{P_2 r^2_1})^{1/2}\)

The peak value, of the electric field (E0 ) of an em wave, (at a point distant r from the source) is related to the power (P) of the source as