In a cylindrical capacitor composed of two coaxial cylinders of radii and () and length , the capacitance per unit length is given by which expression?
Answer and explanation
Correct answer: C.
- Step 1: For a charge per unit length , the electric field at distance () is .
- Step 2: The potential difference between the cylinders is .
- Step 3: Capacitance per unit length is .
Answer
.
Why not the others: omits the factor of 2 in Gauss's line law; is dimensionally incorrect; has spherical geometry factors.
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