Introduction to Electricity
Understanding the basics of electric charge, current, and voltage - the foundation of all electronics.
Electricity is the flow of tiny particles called electrons through a material. These electrons carry electric charge, and when they move together in the same direction, we call this flow electric current. Understanding voltage, current, and resistance is essential for all electronics work.
Objectives
- Understand what electric charge is and how it relates to atoms
- Define voltage, current, and resistance with their units
- Recognize basic circuit symbols and read simple schematics
- Understand how batteries combine in series and parallel
- Know common voltage and current values for everyday devices
- Be prepared to learn Ohm's Law
Key Takeaways
- Voltage (V) is the "push" measured in Volts
- Current (I) is the "flow rate" measured in Amperes
- Resistance (R) is the "opposition" measured in Ohms
- Batteries in series: voltages add, capacity unchanged
- Batteries in parallel: voltage unchanged, capacity adds
- These three quantities are related by Ohm's Law: V = I × R
Practice Problems
Problem 1: If 5 Coulombs of charge pass through a wire in 2 seconds, what is the current?
Problem 2: Four 1.5V batteries are connected in series. What is the total voltage?
Problem 3: You have two 9V batteries. How would you connect them to get 18V?
Problem 4: A circuit has 12V across it and 2A of current flowing. Using R = V/I, what is the resistance?