Electromagnetic radiation from a lamp

[quantumlolz]

Homework Statement

What is the peak electric field E_0 at 1 m from a 100 W lamp. Assume spherically uniform emission

Homework Equations

Magnitude of Poynting vector $$S = \frac{E_0^2}{c\mu_0}$$
And Power = S x Area (2)

The Attempt at a Solution

Sub for S from (1) in (2) and rearranging: $$E_0 = \sqrt{\frac{cP\mu_0}{A}}$$

is A just then $$4\pi d^2$$ where d = 1m?

Then after that just plugging in numbers?

 

[jbsteele]

E_0 = \sqrt{\frac{cP\mu_0}{4\pi d^2}} E_0 = \sqrt{\frac{3.00\times 10^8 \times 100 \times 4\pi\times (1\times 10^-3)^2}{4\pi}} E_0 = 1.86 \times 10^5 V/m