Question 183: EM waves

Question

Suppose that intensity of a laser is $${{315} \over \pi }$$ W/m2. The rms electric field, in units of V/m associated
with this source is close to the nearest integer is __________.
$$ \in $$0 = 8.86 × 10–12 C2 Nm–2; c = 3 × 108 ms–1)

Accepted Answer

I = $${1 \over 2}$$$$\varepsilon $$
0
$$E_0^2$$c
$$ \Rightarrow $$ E
0
= $$\sqrt {{{2I} \over {{\varepsilon _0}c}}} $$
$$ 	herefore $$ E
rms
= $${{{E_0}} \over {\sqrt 2 }}$$ = $$\sqrt {{I \over {{\varepsilon _0}c}}} $$
= $$\sqrt {{{{{315} \over \pi }} \over {8.86 	imes {{10}^{ - 12}} 	imes 3 	imes {{10}^8}}}} $$
= 194

EM waves

Suppose that intensity of a laser is ${{315} \over \pi } W/m2. The rms electric field, in units of V/m associated with this source is close to the nearest integer is __________. \in $0 = 8.86 × 10–12 C2 Nm–2; c = 3 × 108 ms–1)

Choose the correct answer: