Question

What is the radiation resistance of the antenna radiating at 5kW and having maximum current 2A?

(a) 25kΩ

(b) 2.5kΩ

(c) 0.25kΩ

(d) 2.5Ω

Answer 1

Right option is (b) 2.5kΩ

Explanation: (I_{rms}=frac{I_m}{sqrt{2}}=frac{2}{sqrt{2}}=sqrt{2})

Power radiated (P_{rad}=I_{rms}^2 R_{rad})

⇨ (R_{rad}=frac{P_{rad}}{I_{rms}^2} = frac{5K}{2}=2.5kOmega)