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AP Physics C: Electricity & Magnetism 8.4 A Describe the Electric Field Resulting From a Given Charge Distribution Questions

Determine the electric field resulting from a continuous charge distribution by modeling charge density and integrating field contributions.

Syllabus
Effective Fall 2024
Course
AP Physics C: Electricity & Magnetism

Exam points

  • express a charge element or total charge from linear density with correct variables and limits
  • use symmetry to cancel field components and determine the surviving field direction
  • set up and evaluate a Coulomb-law integral for a finite wire, ring, or circular arc
  • take a far-field limit and recover the point-charge field of the distribution's total charge
  • interpret or sketch field, acceleration, or velocity variation with position near a distribution

AP Physics C: Electricity & Magnetism 8.4 A Describe the Electric Field Resulting From a Given Charge Distribution Questions question 1

[Maximum number: 2]

A nonconducting rod of uniform negative linear charge density is near a sphere with charge +1.0 nC. The rod and sphere are held at rest on the y-axis, as shown in Figure 1. Equipotential lines and positions A, B, C, D, and E are labeled. Adjacent tick marks on the x-axis and on the y-axis are 0.40 m apart.

The electric potential VPV_{\mathrm{P}} at yPy_{\mathrm{P}} is VP=−kλln⁡(yPyP−2L)V_{\mathrm{P}}=-k \lambda \ln \left(\frac{y_{\mathrm{P}}}{y_{\mathrm{P}}-2 L}\right).

On Figure 4, sketch a graph of the y-component EyE_{y} of the electric field resulting from the rod as a function of y in the region 2 L<y<12 L.

Figure 4

Figure 4

Figure 1

Figure 1

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