Answer:
The correct answer is:
(a) [tex]3.31\times 10^{10} \ \omega/m^2[/tex]
(b) [tex]5\times 10^6 \ N/C[/tex]
Explanation:
The given values are:
Power of Laser beam,
= 10 mW
on converting it, we get
= [tex]10\times 10^{-3} \ \omega[/tex]
= [tex]10^{-2} \ \omega[/tex]
Spot's diameter,
= 0.62 μm
= [tex]0.62\times 10^{-6} \ m[/tex]
Now,
(a)
The intensity of light will be:
⇒ [tex]I=\frac{P}{\pi r^2}[/tex]
or,
⇒ [tex]=\frac{4P}{\pi d^2}[/tex]
On substituting the values, we get
⇒ [tex]=\frac{4\times 10^{-2}}{\pi(0.62)^2\times 10^{-12}}[/tex]
⇒ [tex]=3.31\times 10^{10} \ \omega/m^2[/tex]
(b)
The amplitude of electric field will be:
⇒ [tex]I=\frac{1}{2}\epsilon_0E_0.C[/tex]
or,
⇒ [tex]E_0=\sqrt{\frac{2I}{CE_0} }[/tex]
On substituting the values, we get
⇒ [tex]=\sqrt{\frac{3.31\times 10^{10}\times 2}{3\times 10^8\times 8.85\times 10^{-12}} }[/tex]
⇒ [tex]=5\times 10^6 \ V/m[/tex]
