Voltage, current, resistance and power are enough to explain a surprising amount of practical electronics. Change the controls, watch the numbers move, and build intuition before memorizing formulas.
Voltage (V) is the electrical potential difference that can push charge through a circuit. Current (I), measured in amperes, is the rate at which charge flows. Resistance (R), measured in ohms, opposes that flow. Power (P), measured in watts, tells you how quickly electrical energy is converted into heat, light, motion or computation.
A circuit needs a closed path. An open switch breaks the path, so current stops. A short circuit removes too much resistance and can allow dangerously high current; protection devices and correct design exist for that reason.
For an ideal resistor, any two values determine the third. Move the sliders and observe how current and power react.
Increase voltage or reduce resistance to increase current.
Power is energy per second. In real hardware it determines heat, wire/component ratings and energy use. The three formulas are equivalent; use whichever matches the values you know.
Components have power limits. A resistor dissipating 0.4 W should not be treated as safe merely because its resistance value is correct if it is only rated for 0.25 W.
Most circuits are combinations of a small set of building blocks.
Provides the voltage that drives current through the circuit.
Limits and controls current, dissipating electrical energy as heat.
Emits light when forward biased. It normally needs current limiting rather than being connected directly across a supply.
Stores energy in an electric field. Useful for filtering, smoothing and timing.
Stores energy in a magnetic field and opposes rapid changes in current.
Conducts strongly in one direction and blocks in the other within its ratings.
An electrically controlled switch or amplifier. Billions of transistors form modern processors.
Opens or closes the current path.
An adjustable resistor, often used as a divider or control input.
Converts electrical energy into mechanical motion.
Two identical resistive loads in series share the supply voltage. In parallel, each branch receives the full supply voltage.
Equivalent resistance adds: Req = R₁ + R₂. The same current flows through both loads.
For equal resistors, Req = R/2. Each branch sees the full source voltage, so total source current is higher.