Ch. 22 Homework, pt. 2 Begin Date: 3/12/2018 2:00:00 PM-Due Date: 3/14/2018 5:00
ID: 1585764 • Letter: C
Question
Ch. 22 Homework, pt. 2 Begin Date: 3/12/2018 2:00:00 PM-Due Date: 3/14/2018 5:00: 00 PM End Date: 3/16/2018 9:59:00 AM (25%) Problem 2: Assume the helium-neon lasers commonly used in student physics laboratories have power outputs of 0.75 mW. Randomized Variables P = 0.75 mW d=2.8 mm × 33% Part (a) If such a laser beam is projected onto a circular spot 2.8 mm in diameter, what is its intensity in W/m r? Grade Summary Deductions Potential I = 6631 90 sinO cosO inO 7 8 9 HOME tan() acosO Submissions Attempts remaining (4% per attempt) detailed view cotan) as acotan) sinh coshO tanh cotanhO o Degrees Radians 0 END 4% VO BACKSPACE DEL CLEAR Submit Hint I give up! Hints: 1%-deduction per hint. Hints remaining: 2 Feedback: 1% deduction per feedback. 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
Given that,
P = 0.75 W
diameter d = 2.8 mm
radius r = 1.4 mm
(a)
lntensity l = P / A
l = 0.75*10^(-3) / pi*(1.4*10^(-3))^2
l = 121.8 W/m^2
(b)
Peak magnetic field strength,
B = sqrt (2*u0*l / c)
B = sqrt (2*4*pi*10^(-7)*121.8 / 3*10^8)
B = 1.01*10^(-6) T
(c)
Peak electric field strength,
E = sqrt (2l / c*e0)
E = sqrt (2*121.8 / 3*10^8*8.85*10^(-12))
E = 302.97 V/m