Lesson: The Power of Electrical Components Physics • 9th Grade

In this lesson, we will learn how to use the formula E = QV to find the energy dissipated to the environment by the component of an electronic circuit.

Lesson Plan

Objectives

Students will be able to

use to determine the energy gained or lost, , by a charge moving across a potential difference ,
use to find the power of a circuit component given the current, , through it and the potential difference, , across it,
use .

Prerequisites

Students should already be familiar with

using to calculate the current, , through a circuit component given the charge, , that passes through it in time ,
Ohm’s law: ,
using to find the power, , of a circuit component given the amount of energy transferred by it, , in time ,
adding potential differences and resistances in series,
adding currents in parallel.

Exclusions

Students will not cover

alternating current circuits,
electrical power transmission,
transformers,
the conservation of energy in circuits,
Kirchhoff’s laws.

Lesson Video

Sample Question Videos

00:54
01:15
02:19

Lesson Worksheet

Q1:

A 7 Ω resistor and a 5 Ω resistor are connected in series to a cell. The cell provides a current of 4 A through the circuit. How much energy do the resistors transfer to the surrounding environment in 20 seconds?

Q2:

Which of the following is the correct formula for the energy transferred to the environment when an amount of a charge, , is moved across a potential difference, ?

Q3:

An electric motor is connected to a 9 V battery. Over a period of time, the motor converts 450 J of electrical energy into kinetic energy, heat, and sound. How much charge passes through the motor over this period of time?