5. + -2 points OSColPhys1 24.P034.Tutorial.WA. My Notes The helium-neon lasers m

Question

5. + -2 points OSColPhys1 24.P034.Tutorial.WA. My Notes The helium-neon lasers most commonly used in student physics laboratories have average power outputs of 0.250 mW. (a) If such a laser beam is projected onto a circular spot 4.66 mm in diameter, what is its intensity? W/m2 (b) Find the peak electric field strength V/m (c) Find the peak magnetic field strength 2 Tutorial Supporting Materials Physical Constants Viewing Saved Work Revert to Last Response Submit Answer Save ProgressPractice Another Version

Explanation / Answer

a)

I = P/A

where P = 0.250 x 10^-3 W

r = d/2 = (4.66 x 10^-3) / 2 = 2.33 x 10^-3 m

A = pi*r^2 = pi x (2.33 x 10^-3 m)^2 = 1.71 x 10^-5 m^2

I = P / A

I = (0.250 x 10^-3 W) / (1.71 x 10^-5 m^2)

I = 14.62 W/m^2

first solving c)

I = ce0 E^2/2

14.62 = (3 x 10^8 x 8.854 x 10^-12 x E^2) / 2

E = 104.92 N/C

b)

B = E/C

B = 104.92 N/C / (3 x 10^8 m/s)

B = 3.5 x 10^-7 T

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