Lesson: Energy, Power, and Intensity of Electromagnetic WavesPhysics
In this lesson, we will learn how to calculate the energy, power, and intensity of electromagnetic waves and the magnitude of the Poynting vector.
Sample Question Videos
An outdoor WiFi unit for a picnic area has an output of 100 mW and a range of 30 m. What output power would reduce its range to 12 m for use with the same devices as before? Assume that there are no obstacles between the unit and the picnic area and that microwaves incident on the ground are completely absorbed.
Two lightbulbs have electrical power inputs of 100 W and 75 W respectively. At what distance is the intensity of light produced by the 100 W lightbulb equal to the intensity of light 10.0 m away from the 75 W lightbulb? Assume that both lightbulbs have the same efficiency.
What is the intensity of an electromagnetic wave with a peak electric field strength of 125 V/m?