Skip to ContentGo to accessibility pageKeyboard shortcuts menu
OpenStax Logo
Physics

Section Summary

PhysicsSection Summary

19.1 Ohm's law

  • Direct current is constant over time; alternating current alternates smoothly back and forth over time.
  • Electrical resistance causes materials to extract work from the current that flows through them.
  • In ohmic materials, voltage drop along a path is proportional to the current that runs through the path.

19.2 Series Circuits

  • Circuit diagrams are schematic representations of electric circuits.
  • Resistors in series are resistors that are connected head to tail.
  • The same current runs through all resistors in series; however, the voltage drop across each resistor can be different.
  • The voltage is the same at every point in a given wire.

19.3 Parallel Circuits

  • The equivalent resistance of a group of N identical resistors R connected in parallel is R/N.
  • Connecting resistors in parallel provides more paths for the current to go through, so the equivalent resistance is always less than the smallest resistance of the parallel resistors.
  • The same voltage drop occurs across all resistors in parallel; however, the current through each resistor can differ.

19.4 Electric Power

  • Electric power is dissipated in the resistances of a circuit. Capacitors do not dissipate electric power.
  • Electric power is proportional to the voltage and the current in a circuit.
  • Ohm’s law provides two extra expressions for electric power: one that does not involve current and one that does not involve voltage.
Order a print copy

As an Amazon Associate we earn from qualifying purchases.

Citation/Attribution

This book may not be used in the training of large language models or otherwise be ingested into large language models or generative AI offerings without OpenStax's permission.

Want to cite, share, or modify this book? This book uses the Creative Commons Attribution License and you must attribute Texas Education Agency (TEA). The original material is available at: https://www.texasgateway.org/book/tea-physics . Changes were made to the original material, including updates to art, structure, and other content updates.

Attribution information
  • If you are redistributing all or part of this book in a print format, then you must include on every physical page the following attribution:
    Access for free at https://openstax.org/books/physics/pages/1-introduction
  • If you are redistributing all or part of this book in a digital format, then you must include on every digital page view the following attribution:
    Access for free at https://openstax.org/books/physics/pages/1-introduction
Citation information

© Jan 19, 2024 Texas Education Agency (TEA). The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University.