HW-7Solutions-01-26-08 - Physics 21 Spring 2008 HW-7...

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

Physics 21, Spring 2008 January 26, 2008 HW-7 Solutions 7-1. (HRW 25-53) The space between two concentric conducting spherical shells of radii b = 1.70 cm and a = 1.20 cm is filled with a substance of dielectric constant κ = 23.5. A potential difference V = 73.0 V is applied across the inner and outer shells. Determine (a) the capacitance of the device, (b) the free charge q on the inner shell, and (c) the charge q’ induced along the surface of the inner shell. Solution: (a) According to Eq. 25-17 the capacitance of an air-filled spherical capacitor is given by 0 0 4 . ab C b a ε = π When the dielectric is inserted between the plates the capacitance is greater by a factor of the dielectric constant κ . Consequently, the new capacitance is 0 9 2 2 23.5 (0.0120 m)(0.0170 m) 4 0.107 nF. 8.99 10 N m C 0.0170 m 0.0120 m ab C b a κε = = = × π (b) The charge on the positive plate is (0.107 nF)(73.0 V) 7.79 nC. q CV = = = (c) Let the charge on the inner conductor be – q . Immediately adjacent to it is the induced charge q' . Since the electric field is less by a factor 1/
Image of page 1

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

Image of page 2
This is the end of the preview. Sign up to access the rest of the document.
  • Spring '08
  • Kim
  • Physics, Energy, Potential difference, Electric charge, Dielectric

{[ 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