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Resistance, Resistivity, and Ohm's Law

Mia Gonzalez

Mia Gonzalez

6 min read

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Study Guide Overview

This study guide covers resistance, Ohm's Law (V=IRV=IR), and circuit elements. It explains resistivity, the relationship between resistance, material dimensions, and ohmic materials. The guide also discusses energy dissipation in resistors and provides practice questions and exam tips.

AP Physics C: E&M - Resistance, Ohm's Law, and Circuit Elements ⚡

Hey, future physicist! Let's get you prepped for the AP exam with a super-focused review of resistance, Ohm's Law, and circuit elements. This is your go-to guide for a quick, effective study session the night before the test.

Foundational Concepts: Resistance and Ohm's Law

These are the building blocks of circuit analysis. Understanding them is key to tackling more complex problems. Let's dive in!

Ohm's Law

  • Definition: Ohm's Law describes the relationship between voltage (VV), current (II), and resistance (RR) in a circuit: V=IRV = IR

Key Concept

This equation is your bread and butter! Remember it well, as it's used in almost every circuit problem.

  • Voltage (VV): The electrical potential difference across a component, measured in volts (V).
  • Current (II): The flow of electric charge, measured in amperes (A).
  • Resistance (RR): The opposition to the flow of current, measured in ohms (Ω).

Resistivity

  • Definition: Resistivity (hoho) is a material's intrinsic property that measures how strongly it opposes the flow of electric current. It's measured in ohm-meters (Ω⋅m).
  • Key Point: Unlike resistance, which depends on the dimensions of the material, resistivity is a property of the material itself.

Resistance

  • Definition: Resistance (RR) is the measure of how much a material opposes the flow of electric current. It depends on the material's resistivity (hoho), length (LL), and cross-sectional area (AA): R=ρLAR = \frac{\rho L}{A}
Memory Aid

Think of it li...

Question 1 of 10

A circuit has a current of 2A flowing through a 6Ω resistor. What is the voltage across the resistor? ⚡

3 V

8 V

12 V

24 V