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AP® Physics 2: Algebra-Based · Unit 10 · Topic 10.7

Conservation of Electric Energy: Topic Checklist (Physics 2 10.7)

Specific “I can…” statements for conservation of electric energy, each linked to the guide section and practice question that shows whether you can really do it.

Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.

Understanding

  • I can explain the difference between electric potential (a property of a place, in volts) and electric potential energy (a property of a system, in joules). (Guide: “From potential to potential energy”)
  • I can predict which way a positive or a negative charge moves when released from rest, in terms of potential and field direction. (Guide: “Which way does a released charge move?”; Figure 1)
  • I can explain why a charge that starts and ends on the same equipotential line has the same speed at both points. (Practice Q4)
  • I can choose the system (charge alone, or charge plus field) and use either W_field or ΔU_E without counting the energy twice. (Guide: “Energy conservation for a moving charge”)

Calculation and skills

  • I can calculate ΔU_E = qΔV with the correct sign for a positive or negative charge. (Practice Q1, Q5a)
  • I can use ΔK + ΔU_E = 0 to find the speed of a particle after it crosses a potential difference, starting from rest or already moving. (Guide: Worked example 1; Practice Q5, Q7)
  • I can find the potential difference needed to stop a moving charge, or its distance of closest approach to a fixed charge. (Guide: Worked example 2; Practice Q5c)
  • I can derive a symbolic expression for the speed of a charge released near a fixed point charge. (Practice Q6)
  • I can sketch U_E and K against position for a uniform field and for a fixed point charge. (Guide: “Energy graphs”; Practice Q3, Q6d, Q7c)

Reasoning

  • I can compare the kinetic energies and speeds of two particles with different charges and masses crossing the same ΔV. (Practice Q2)
  • I can explain why changing the plate spacing, with the same potentials, does not change the final speed. (Practice Q7d)
  • I can check an answer by a second method, such as forces and kinematics in a uniform field. (Guide: Worked example 1)

All ticked? Move on to Topic 11.1, Electric Current, or return to the course roadmap.

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