You already know that current flows through a circuit at some voltage and meets some resistance along the way. Ohm's Law ties those three together: V = I x R, so the current through a bulb is its voltage divided by its resistance. Now look at how the parts are arranged. There are two main patterns: series and parallel.
In a series circuit, there is only one path for current to flow. That means the current is exactly the same at every point in the loop. The voltage, though, splits: each part uses some of it, and those voltage drops add up to the battery's total voltage. Break that single path anywhere and everything in the loop stops at once.
In a parallel circuit, the parts sit on separate branches. Each branch connects straight across the battery, so every branch gets the full voltage. The current is what splits this time: it divides between branches, and those branch currents add up to the total current the battery supplies.
Every lamp in your house is wired in parallel, so each one gets full voltage and works on its own path. Turn off one light and the others stay on. Old-style Christmas lights are wired in series instead, so one broken bulb breaks the only path, and the whole string goes dark.
Series shares one path, so current stays the same while voltage splits; parallel gives every branch full voltage while the currents add up.
Last time you tied V, I and R together with V = I x R. The class torch runs one bulb on its 6V battery, and the ammeter reads 2A. Zoe wants a second bulb in there so the beam covers more ground, and Omar wires it into the same single loop.
The battery still gives 6V. With both bulbs in that one loop, what does each bulb get?
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