{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

HW18Sol - Jim Guinns PHYS2212 Assignment#18 Solutions 1 An...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Jim Guinn’s PHYS2212 Assignment #18 Solutions 1. An electromagnetic wave has an intensity of 1.00x10 2 W/m 2 . Find the magnitude of the electric and magnetic field. (You are actually getting the average magnitude. More on this later.) The energy density of the wave is then given by U = S / c = (100W/m 2 ) / (3.00x10 8 m/s) = 3.33x10 -7 J/m 3 , half of which, 1.67x10 -7 J/m 3 , is in the electric field and half in the magnetic field. So U E = (1/2) ε o E 2 or E = √ (2U E / ε o ) = E = 194V/m , and B = E / c = B = 6.47x10 -7 T . 2. The intensity of the sunlight at the top of Earth's atmosphere is 1390 W/m 2 . What is the amplitude of the electric and magnetic field at this point? You may treat the light as having a single wavelength. The intensity of a light source is given by S = c u , where u = the light's energy density, so u = S / c = 1390 W/m 2 / 3.00x10 8 m/s = 4.63x10 -6 J/m 3 . The energy density is given by u = ε o E rms 2 , so E rms = √(u/ ε o ) = 724. N/C , and E o = √2 E rms = E o = 1020 N/C . The amplitude of the magnetic field is then given by B o = E o / c = (1020 N/C) / (3.00x10 8 m/s) = B o = 3.40x10 -6 T . 3. An electromagnetic wave has an electric field amplitude of 1.00V/m . What is the average intensity of the wave? The magnetic field amplitude is given by
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern