A light-emitting diode (LED) converts electricity to approximately sinusoidal electromagnetic waves with a definite frequency $f$. Imagine that light from the LED creates an oscillating electric field with amplitude $E_{0}$ at a certain location. If we increase the electrical power to the LED so that the oscillation amplitude is now $2 E_{0}$, by what factor have we increased the power?
A) 4 times
B) 2 times
C) $\sqrt{2}$ times
D) One cannot answer without more information.

Question

Quizplus · Accepted Answer

The power of an electromagnetic wave is proportional to the square of the amplitude of the electric field. Therefore, if the amplitude is doubled from $E_0$ to $2E_0$, the power increases by a factor of $(2E_0)^2 / (E_0)^2 = 4$.

A Light-Emitting Diode (LED) Converts Electricity to Approximately Sinusoidal Electromagnetic fff

A Light-Emitting Diode (LED) Converts Electricity to Approximately Sinusoidal Electromagnetic $f$