A capacitor is formed from two concentric spherical conducting shells separated by vacuum. The inner sphere has radius 11.5cm , and the oute

Question

A capacitor is formed from two concentric spherical conducting shells separated by vacuum. The inner sphere has radius 11.5cm , and the outer sphere has radius 16.5cm . A potential difference of 100V is applied to the capacitor.

What is the energy density at r= 11.6cm , just outside the inner sphere?

What is the energy density at r = 16.4cm , just inside the outer sphere?

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Thu Cúc 5 years 2021-08-20T18:30:14+00:00 1 Answers 8 views 0

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  1. MichaelMet
    0
    2021-08-20T18:31:44+00:00
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    Answer:

    Explanation:

    radius of inner sphere, a = 11.5 cm = 0.115 m

    radius of outer sphere, b = 16.5 cm = 0.165 m

    Voltage, V = 100 V

    the capacitance of the spherical capacitor is given by

    C = \frac{4\pi \epsilon _{0}ab}{b-a}

    C = \frac{0.115\times 0.165}{9\times 10^{9}\left ( 0.165-0.115 \right )}

    C = 4.22 x 10^-11 F

    Charge, Q = c x V

    Q = 4.22 x 10^-11 x 100

    Q = 4.22 x 10^-9 C

    (a) r = 11.6 cm = 0.116 m

    The electric field at a distance r is given by

    E=\frac{KQ}{r^{2}}

    Where, K is the Coulombic constant

    E=\frac{9\times 10^{9}\times 4.22\times 10^{-9}}{0.116\times 0.116}

    E = 2820.3 N/C

    The energy density is given by

    u = \frac{1}{2}\epsilon _{0}E^{2}

    u = \frac{1}{2}\times 8.854\times 10^{-12}\times 2820.3^{2}

    u = 3.52 x 10^-5 J/m³

    (b) r = 16.4 cm = 0.164 m

    The electric field at a distance r is given by

    E=\frac{KQ}{r^{2}}

    Where, K is the Coulombic constant

    E=\frac{9\times 10^{9}\times 4.22\times 10^{-9}}{0.164\times 0.164}

    E = 1412.1 N/C

    The energy density is given by

    u = \frac{1}{2}\epsilon _{0}E^{2}

    u = \frac{1}{2}\times 8.854\times 10^{-12}\times 1412.1^{2}

    u = 8.83 x 10^-6 J/m³

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