Final answer:
More power is generated with three-phase and high-frequency equipment than with single-phase due to higher current and power factor at resonance and the relationship between induced emf and magnetic flux change.
Step-by-step explanation:
More power is generated when three-phase equipment and high frequency equipment are used than when single phase equipment is used. This occurs because both the current and the power factor are greater at resonance, which leads to significantly greater power output than at higher and lower frequencies. Furthermore, the efficiency of power transmission can be improved with three-phase systems, and with higher frequencies like 400 Hz used in military aircraft, the equipment can be lighter and more compact as well. An increase in the frequency of rotation of the coils in an electrical generator, for instance, increases the output electro-motive force (emf) because the induced emf is proportional to the rate of change of magnetic flux with respect to time. Thus, two factors contribute to greater power production in three-phase and high frequency systems: the increased current and power factor at resonance, and the proportional relationship between induced emf and the rate of magnetic flux change.