From question 7 I at 1 m = I0X108 = 1X10-12X108 = 1x10-4 W/m2

Also I = P/4 r2

P = I(4 r2) = (1X10-4 W/m2)(4p )(1.0 m)2 = 4 X10-4 W

Answer is A

Return