(3%) Problem 18: Assume the helium-neon lasers commonly used in student physics

Question

(3%) Problem 18: Assume the helium-neon lasers commonly used in student physics laboratories have power outputs of 0.55 mW. Randomized Variables P=0.55 mW d=2.2 mm 33% Part (a) If such a laser beam is projected onto a circular spot 2.2 mm in diameter, what is its intensity in W/m2? Grade Summary Deductions 0% Potential 100% Submissions Attempts remaining: 3 (30% per attempt) detailed view sin0 tan() cosO cotanOasin) acosO atanO acotan)sinh(0 cosh0 tanh) cotanh0 123 END Degrees Radians DEL CLEAR Submit Hints: Feedback: là 33% Part (b) Find the peak magnetic field strength in T 33% Part (c) Find the peak electric field strength in V/m

Explanation / Answer

here,

output power , P = 0.55 mW

P = 0.55 * 10^-3 W

part (a)

diameter of spot , d = 2.2 mm

d = 2.2 * 10^-3 m

radius of spot , r = 1.1 * 10^-3 m

Intensity of laser , I = power / area

I = 0.55 * 10^-3 / (pi * 1.1^2 * 10^-6 )

I = 144.76 W/m^2

the intensity is 144.76 W/m^2

part (b)

let the peak magnetic feild be B

intensity , I = 0.5 * B^2 * c / u0

144.76 = 0.5 * B^2 * 3 * 10^8 / u0

B = 1.1 * 10^-6 T

the peak magnetic feild strength is 1.1 * 10^-6 T

part (c)

let the peak electric feild be E

E = B * c

E = 1.1 * 10^-6 * 3 * 10^8

E = 330 V/m

the peak electric feild strength is 330 V/m

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