#AP Physics 2: Electric Circuits - The Night Before ⚡

Hey! Let's get you prepped for the AP Physics 2 exam with a super-focused review of electric circuits. We'll make sure everything is crystal clear and you're feeling confident. Let's do this!

#Unit 4: Electric Circuits Overview 🔌

This unit is all about understanding how electric charges move and behave in circuits. We'll cover everything from basic concepts to more complex circuit analysis. Remember, many AP questions combine concepts from different units, so keep an eye out for those connections!

• Key Topics: Electric charge, current, resistance, power, Ohm's Law, series and parallel circuits, and capacitors.
• Big Picture: Understanding how these components work together is key to mastering the unit.

# 4.1 Definition and Conservation of Electric Charge 🔋

• Electric Charge (q): A fundamental property of matter, measured in Coulombs (C). It can be positive or negative.

  • Like charges repel, opposite charges attract. Think of magnets, but with electricity!

• Conservation of Electric Charge: The total charge in an isolated system remains constant. Charge isn't created or destroyed, just transferred. 💡

• Implications:
  • In a closed circuit, the total charge is constant.
  • Charge flow (current) is the movement of these charges.
  • Kirchhoff's Laws are based on this conservation principle.

# 4.2 Resistivity and Resistance 🚧

• Resistance (R): How much a material opposes the flow of electric current, measured in ohms (Ω).

• Resistivity (ρ): An inherent property of a material that determines its resistance, measured in ohm-meters (Ω⋅m). It depends on temperature.

• Formula:

  $$R = \frac{\rho L}{A}$$

  • R = Resistance

  • ρ = Resistivity

  • L = Length of the material

  • A = Cross-sectional area