Observe each circuit diagram and label it as open or closed.

Let's analyze each of the six circuit diagrams and determine whether each circuit is open or closed.

Definitions:

- A closed circuit has a complete path for current to flow from the power source (battery) through the components (like bulbs) and back to the source.
- An open circuit has a break in the path — such as an open switch or disconnected wire — so current cannot flow.

Now, let’s go through each diagram:

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1)
- Battery → two bulbs in series → one bulb → back to battery.
- There are no switches or breaks visible.
✔ The path is continuous.
➡️ Closed Circuit

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2)
- Battery → one bulb → switch → another bulb → back to battery.
- The switch is open (it's shown in the "up" position).
✘ Break in the circuit due to open switch.
➡️ Open Circuit

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3)
- Battery connected to two parallel branches, each with a bulb.
- A switch is in the main line (before the split), and it is open.
✘ Since the main switch is open, no current can flow into either branch.
➡️ Open Circuit

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4)
- Battery → three resistors/bulbs in series → one bulb → back to battery.
- No switch is present. All connections appear continuous.
✔ Complete path exists.
➡️ Closed Circuit

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5)
- Battery → switch → two bulbs in series → back to battery.
- The switch is open (shown in the "up" position).
✘ Break in the circuit.
➡️ Open Circuit

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6)
- Battery → switch → two bulbs in parallel → back to battery.
- The switch is closed (shown in the "down" position).
✔ Path is complete; current can flow through both bulbs.
➡️ Closed Circuit

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Final Answers:

1) Closed
2) Open
3) Open
4) Closed
5) Open
6) Closed

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✔ Summary:
- Closed circuits: 1, 4, 6
- Open circuits: 2, 3, 5

These labels reflect whether there is a complete conductive path for electricity to flow.