Series: One Path

Lesson 5 of 10 · 7 min · Free, no account needed

What you will learn

In series there is one path: the same current flows through every part, and one break stops them all.
Resistances in series add: R_total = R1 + R2 + ..., so each extra bulb makes the current smaller.
The battery's voltage is shared: the voltages across the parts add up to the battery voltage.

Old holiday lights: one bulb dies and the whole string goes dark. Tap every bulb that goes dark when bulb 3 is unscrewed.
In series the charge has one path. Unscrewing a bulb opens the loop, so the current stops everywhere at once.
Add bulbs to the row, one at a time.
Watch the bulbs and the ammeter.
Measure the voltage across each bulb.
Put the probes on the two contacts of a bulb. Do all three.
One path is called a series circuit.
In a series circuit there is one path: the same current flows through every part.
Resistances in series add: R_total = R1 + R2 + .... More parts, less current.
The battery's voltage is shared: the voltages across the parts add up to it.
Game: Find the dead bulb. One of these 8 is broken. Find it in as few measurements as you can.
Move the probes to measure, then tap the bulb you think is dead.
Each bulb is made for 1.5 V. How many in a row on a 9 V battery?
Identical parts in series share the voltage equally: V each = V total ÷ n. 9 V ÷ 6 = 1.5 V.
Code: computers find faults by splitting the search in half. Step through it.
Bulb 6 of 8 is dead, as in your game.
A 2 Ω and a 4 Ω resistor in series on 12 V. What is the current?
Series: R_total = 2 + 4 = 6 Ω, then I = V ÷ R = 12 ÷ 6 = 2 A.
Race: your measurements against binary search.

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