Open and Closed Circuits worksheet for students to identify circuit states.

Let me carefully examine each circuit diagram to determine whether it is open or closed.

I'll go one by one:

1) Circuit 1: There's a battery, two wires, and a light bulb. The wires form a complete loop from the battery through the bulb and back. No switches are open — everything is connected. So this is a closed circuit.

2) Circuit 2: Battery, two bulbs, and a switch. The switch is shown in the *open* position (the lever is up, not touching both contacts), so the path is broken. That means current cannot flow. This is an open circuit.

3) Circuit 3: Battery, three bulbs, and a switch. The switch is drawn with a gap — it's open — and it’s in series with one of the branches. Since the switch is open, that branch is broken, but wait — let me check if the rest forms a complete path. Actually, looking more closely: the switch is in one parallel branch, but the other branches are connected directly. However, for the whole circuit to be closed, there must be at least one complete path from battery positive to negative. Here, the top wire connects battery + to all bulbs, and the bottom wire connects all bulbs back to battery – but the switch is in series with one bulb only. Even if that branch is open, the other two bulbs still have a full path. Wait — no: look again. All three bulbs share the same top and bottom rails. The switch is in series with the middle bulb — but since the rails are continuous, current can still flow through the left and right bulbs. So the circuit as a whole is still closed (current can flow). But the question is about the *circuit*, not individual paths. In standard interpretation, if there's any complete conducting path from battery + to −, the circuit is considered closed. So yes — this is closed.

Wait — hold on. Let me double-check standard teaching for this level. In elementary circuits like this, if a switch is open *anywhere in the main path*, it breaks the circuit. But here, the switch is only in one parallel branch. The main loop (battery → left bulb → back) is intact. So the circuit is closed.

But many worksheets treat it as: if the switch is open, and it's part of the diagram, they want you to say "open" only if *no* current can flow. Let me verify with diagram 4.

4) Circuit 4: Battery, one bulb, and two open connection points (the little circles with gaps — those represent an open switch or break). Yes, those are clearly open — no wire connecting them. So current cannot flow. This is open.

5) Circuit 5: Battery, two bulbs in series, and a switch. The switch is drawn with a gap — open position. So the loop is broken. This is open.

6) Circuit 6: Battery, a switch (open), and two bulbs in parallel. Again, the switch is in the main path before the parallel branches — so if the switch is open, no current reaches either bulb. So this is open.

Wait — let me re-express clearly with standard conventions used in such worksheets:

- A circuit is closed if there is a complete, unbroken path for electricity to flow from the battery’s positive terminal, through components, and back to the negative terminal.
- A switch drawn with a gap (lever not touching) = open = breaks the path.
- In parallel circuits, if the switch is in the main line (before branches), opening it opens the whole circuit.
- If the switch is only in one branch, the other branches may still work — but many school-level worksheets simplify and consider the *entire diagram* as “open” if any switch is open, unless specified otherwise.

Looking again at diagram 3: the switch is in series with the middle bulb, but the left and right bulbs are directly connected across the battery. So current *can* flow through left and right bulbs. Therefore, the circuit is closed.

However, I should zoom in to confirm the wiring precisely.