Question

The antenna current is $8A$ when only a carrier wave is transmitted and $9.6A$ when an AM wave is transmitted. If the carrier power is $10kW$, the modulating power is

• A. $14.4kW$
• B. $1.2kW$
• C. $2kW$
• D. $4.4kW$

Answer 1

The correct option is D $4.4kW$

$\frac{P_{AM}}{P_C}={\left(\frac{I_{AM}}{I_C}\right)}^2$
$\frac{P_{AM}}{10}={\left(\frac{9.6}{8}\right)}^2$
$P_{AM}=10\times 1.44=14.4kW$

Modulating power $=14.4-10=4.4kW$