Lesson 19.3: Electric current is a flow of charge

Lesson Focus

Discover how a continuous flow of charge, or electric current, powers our world. We'll explore the relationship between current, voltage, and resistance, and investigate how different types of electric cells, like batteries, create electricity.

Learning Objectives

• Understand what electric current is and how this continuous flow of charge differs from static electricity.
• Learn how voltage and resistance affect current, and use Ohm's law to calculate their relationship.
• Differentiate between various electric power cells, including primary, storage (rechargeable), and solar cells.
• Conduct a hands-on experiment to see how you can produce an electric current using everyday materials.

Unlike static charge, electric current is a continuous, steady flow of charge through a material, moving from higher to lower potential.

This flow, measured in amperes (amps), is what powers your devices. Think of it like a constant river of charge, not a single splash. What makes this river flow?

The amount of current depends on two things: voltage (the push) and resistance (the opposition).

Ohm's Law explains this relationship with the formula I = V/R. Higher voltage increases current, while higher resistance decreases it. If a 12-volt battery has 6 ohms of resistance, what is the current?

An electric cell is a device that acts like a pump, converting stored energy into a continuous electric current.

It does this by creating a steady voltage between its two terminals.

When connected in a circuit, this voltage pushes charges to flow and power a device like a flashlight or phone.

An electrochemical cell uses chemical reactions to produce current. Primary cells (like D-cells) are non-rechargeable because their chemical reaction is permanent.

Storage cells (like car batteries) are rechargeable because an external current can reverse the chemical reaction, restoring their power. Why can you recharge a phone but not a TV remote battery?

A solar cell produces electric current by absorbing energy from light.

When sunlight hits a special material like silicon, it frees electrons, causing them to flow. Unlike batteries, solar cells don't rely on finite chemical reactants, but they need a light source to work.

What is a major drawback of solar power?