Electric field strength from a light bulb

[A90]

Homework Statement

What is the approximate electric field strength of the electromagnetic waves radiated by a 100-W light bulb, measured 3.0m from the bulb?

Homework Equations

$$\vec{E}=\frac{kq}{d^{2}}$$

$$P=\frac{2kq^{2}a^{2}}{3c^{3}}$$

The Attempt at a Solution

I solved for $q=\sqrt{\frac{3Pc^{3}}{2ka^{2}}}$, and then plugged that into the equation for electric field, and I have all the values I need to solve except for the acceleration, which I'm not sure how to find. I thought about using the second derivative of $x(t)= x~sin(\omega~t)$, but I don't know what to use for $x$, $\omega$ or $t$.

 

[kuruman]

Your model assumes that lightbulb filaments produce light by having a monopole charge $q$ that radiates energy. That's not how light bulbs work. For this calculation, you need to consider the flux of electromagnetic energy through a sphere of radius 3.0 m and relate that flux to the amplitude of the electric field in the electromagnetic plane wave that crosses the sphere.

Edited to correct typo.