Free AP Physics C lesson

E Field from Distributions

This AP Physics C: Electricity & Magnetism lesson is designed for AP Physics C self-study. It includes 4 video lessons, 6 practice questions, and an estimated completion time of 25 minutes.

Video lessons

  1. The Electric Field Due to a Straight Uniformly Charged Wire

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  2. The Electric Field Due to a Straight Uniformly Charged Wire (part 2)

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  3. Electric Field Due to a Ring of Charge

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  4. Electric Field Due to a Semi-Circular Ring of Charge

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Practice covered

  1. For an infinitely long straight wire with uniform linear charge density lambda, the electric field at a perpendicular distance r from the wire is given by E = lambda / 2piepsilon_0 r. How does the field strength vary with distance?
  2. A finite wire of length L = 0.40 m carries a uniform charge of Q = 8.0 times 10^-9 C. Calculate the magnitude of the electric field (in N/C) at a point on the perpendicular bisector, a distance r = 0.30 m from the wire's center. Use the approximation formula for points not too far from a finite wire: E approx kQ / rsqrtr^2 + (L/2)^2. (k = 9.0 times 10^9 , Ncdotm^2/C^2)
  3. A uniformly charged ring of radius R carries total charge Q. At the center of the ring, what is the electric field?
  4. For a ring of radius R with charge Q, the electric field along the axis at distance x from the center is E = kQx / (x^2 + R^2)^3/2. At what distance x (in terms of R) is the field maximum? Enter your answer as a decimal multiple of R (e.g., if x = 0.5R, enter 0.5, or if x = R/sqrt2, enter 0.707).
  5. A uniformly charged disk of radius R has surface charge density sigma. Very close to the disk's center (when x ll R), the electric field approaches:
  6. A semi-circular ring of radius R has uniform charge Q distributed along its length. At the center of curvature, the direction of the electric field is:
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