Basic Electronics
Think of electricity as water in a pipe: voltage (V) is the pressure pushing the water, current (I) is the amount of water flowing, and resistance (R) is how narrow the pipe is. Ohm’s law ties the three together: the greater the pressure and the wider the pipe, the more water flows. The formula fits on one line: V = I × R.
If you connect two resistors in series (end to end), the SAME current must flow through both. The total voltage is therefore shared between them in proportion to their size — the bigger resistor takes the bigger slice of the pie. This simple trick is called a voltage divider, and you will meet it everywhere, from reading sensors to generating references.
Power (P = V × I) is the energy turned into heat inside a resistor. Small resistors typically survive 1/4 W; if your calculated power exceeds that, the part heats up, smells, and burns. Make it a habit: roughly check V²/R every time you pick a resistor.
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