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Physics, 25.10.2021 23:30 dozsyerra

A disk of radius R has positive charge uniformly distributed over an inner circular region of radius a and negative charge uniformly distributed over the outer annular (ring-shaped) region . The surface charge density on the inner region is +σ, and that on the annular region is −σ. The electrostatic potential at P, located on the central perpendicular axis a distance z=R from the disk center, is zero.

What is a?

Express your answer in terms of R. Express the coefficients using three significant digits.

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A disk of radius R has positive charge uniformly distributed over an inner circular region of radius...

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