Home » Power Calculations » 9 » d The power delivered to an antenna is 500 watt. The effective antenna resistance is 20 ohm. The antenna current is:   a.   25 amp   b.   2.5 amp   c.   10 amp   d.   5 amp Your answer "d" is CORRECT! P = I squared x R therefore I = the square root of (P / R) = the square root of (500 / 20) = the square root of (25) = 5 amps. Next