Lesson 19.2: Charges can move from one place to another

Lesson Focus

Static charges don't just sit still; they can move and release stored energy. This lesson explores how charges flow, how their energy is measured, and why some materials conduct electricity while others resist it.

Learning Objectives

• Describe how static charges move from one place to another, transferring energy.
• Explain how charges store potential energy and how this is measured in volts.
• Differentiate between conductors and insulators based on how they affect charge movement.
• Experimentally test and identify which materials are electrical conductors and which are insulators.

Repulsive forces between like charges mean it takes energy to push them together.

This stored energy is electric potential energy. The amount of energy per charge is the electric potential, measured in volts. A charge with high potential is like a stretched rubber band, ready to release its energy.

Charges move from high to low potential, like water flowing downhill.

This movement, called static discharge, releases energy. When you get a shock from a doorknob, the potential difference between you and the metal is great enough to move the charge through the air, creating a spark.

Inside clouds, particles collide, separating charges. The negative bottom of the cloud induces a positive charge on the ground.

When the electric potential difference is huge, a massive static discharge called lightning occurs, releasing energy as light and sound. It's static electricity on a giant scale.

Materials determine if a charge can move.

A conductor, like copper, allows charge to pass through it easily.

An insulator, like the plastic on a wire, blocks the charge's path.

Electrical resistance is how much a material opposes charge flow, measured in ohms (Ω).

High resistance in a thin light bulb filament creates light and heat. Low resistance in thick copper wires lets electricity travel efficiently with less energy wasted. Resistance depends on material, length, and thickness.

Electricity follows the path of least resistance.

Grounding uses this rule for safety by providing a low-resistance wire for dangerous charges to travel directly into the Earth.

A lightning rod is a grounding system that safely directs a lightning strike away from a building, preventing fire and damage.