Turtleand Energy

Foundations

Lesson 1: Electricity from first principles

Start with source, push, flow, resistance, load, power, and energy before memorizing equations.

Electricity is easier to understand when the structure comes before the equations.

A simple circuit has four anchors:

  1. Source: a battery or supply creates electrical push.
  2. Loop: a closed path lets charge keep moving.
  3. Resistance: the path and load limit the flow.
  4. Load: a component turns electrical energy into light, heat, motion, sound, computation, or signal.

Voltage is energy per charge. Current is charge flow per second. Resistance limits current. Power is energy transfer per second. Energy is the amount transferred over time.

The first two equations are enough for the opening lesson:

I = V / R
P = V * I
Energy = P * time

The simulation below lets you adjust voltage, resistance, and time so the relationships become visible while you read.

Simulation

Try the model here.

Adjust voltage, resistance, time, and loop state to see current, power, and transferred energy change together.

Simple circuit model

Push, flow, work, loop.

Closed loop. Current is flowing.

Interactive simple circuit diagramA battery, wire loop, resistance load, and moving charge markers controlled by voltage and resistance sliders.Battery5.0 VLoadResistance20 Ω
Current0.25 A

Current is flow. It rises with voltage and falls with resistance.

Power1.25 W

Power is work per second. It depends on both push and flow.

Energy transferred12.5 J

Energy grows as power continues over time.