Physics worksheet featuring multiple circuit diagrams where students must determine if the light bulbs are lit ("on") or unlit ("off").

Let's go through each circuit one by one and determine whether the bulbs are glowing ("on") or not ("off"). We'll use basic principles of series and parallel circuits, switch states, and current flow.

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🔧 Key Rules:

- A bulb glows if current flows through it.
- In a series circuit, all components must be connected in a continuous loop. If one bulb is broken or switch is off, the whole circuit breaks.
- In a parallel circuit, each branch can operate independently.
- A switch must be closed (on) to allow current.
- A broken path (open switch, disconnected wire) means no current.
- Short circuits (a wire bypassing a bulb) will stop that bulb from glowing.

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Now let’s analyze each circuit:

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✔ Example (Top Left):

```
[Diagram: Three bulbs in parallel; top two have switches, bottom has no switch]
```
- Top bulb: Switch closed → on
- Middle bulb: Switch open → off
- Bottom bulb: No switch, connected directly → on

✔ Answer: on, off, on

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1. First Row, Second Circuit (Top Right)

```
Two bulbs in parallel, both connected directly to battery with no switches.
```
- Both bulbs are in parallel, complete path.
- No switches open.
- ✔ Both bulbs are on

> Answer: both bulbs → on

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2. Second Row, Left Circuit

```
Two bulbs in series, connected to battery.
No switch — circuit is closed.
```
- Series circuit, complete loop.
- ✔ Both bulbs glow.

> Answer: both bulbs → on

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3. Second Row, Right Circuit

```
Bulb A and B in series, C in parallel with switch.
Switch is open.
```
- Bulbs A and B are in series → but there’s a switch in parallel with bulb C.
- Wait: Let's interpret carefully.
- The diagram shows:
- Battery → A → B → back to battery?
- But then C is in parallel with a switch, and this combination is in series with A and B?
- Actually, looking at structure:
- A and B are in series, then C is in parallel with a switch, and this entire group is across the battery?

Wait — better interpretation:
- Battery → A → B → back to battery
- Then C is connected in parallel with a switch, and this C-switch combo is in parallel with the A-B series path?

But actually, it looks like:
- A and B are in series, and C is in parallel with a switch, and that C-switch branch is in parallel with the A-B series path?

But wait — the switch is closed, so it creates a short across bulb C.

So:
- The switch is closed, so it shorts out bulb C → no current through C → C is off
- But A and B are in series, and the circuit is complete → A and B get current → on

> Answer:
- A: on
- B: on
- C: off (shorted)

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4. Third Row, Left Circuit

```
Two bulbs in parallel, connected to battery via a switch.
Switch is open.
```
- Switch is open → no current → both bulbs off

> Answer: both bulbs → off

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5. Third Row, Right Circuit

```
Three bulbs in parallel, connected to battery via a switch.
Switch is open.
```
- Switch is open → no current → all bulbs off

> Answer: all three bulbs → off

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6. Fourth Row, Left Circuit

```
Two bulbs in series, connected to battery via a switch.
Switch is closed.
```
- Closed switch → complete circuit → both bulbs on

> Answer: both bulbs → on

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7. Fourth Row, Right Circuit

```
Three bulbs in parallel, each with its own switch.
Switches are all open.
```
- All switches are open → no current through any bulb → all off

> Answer: all bulbs → off

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8. Fifth Row, Left Circuit

```
Two bulbs in series, connected to battery via a switch.
Switch is closed.
```
- Complete circuit → both bulbs on

> Answer: both bulbs → on

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9. Fifth Row, Right Circuit

```
Two bulbs in parallel, connected to battery.
One bulb has a switch in series with it, which is open.
The other bulb has no switch.
```
- Bulb without switch: direct path → on
- Bulb with switch: switch open → off

> Answer:
- Top bulb: on
- Bottom bulb: off

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10. Sixth Row, Left Circuit

```
Three bulbs in parallel, connected to battery.
One switch is open, others closed.
But the switch is in series with one bulb only.
```
- All bulbs are in parallel.
- One bulb has a switch in series with it → switch open → that bulb off
- Other two bulbs: no switch or switch closed → on

> Answer:
- Left bulb: on
- Middle bulb: on
- Right bulb: off

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11. Sixth Row, Right Circuit

```
Two bulbs in parallel, and a third bulb in series with the battery.
But the switch is open.
Wait — look again.

Actually:
- Battery → one bulb → split into two paths: one with bulb, one with switch.
- But the switch is open → so no current in that branch.
- So only one bulb gets current?

Wait — let's trace:
- Battery → bulb (top) → then splits:
- One path: bulb (middle)
- Other path: switch (open) → so no current
- So only top bulb and middle bulb in series?

Wait — no, the top bulb is in series with the parallel combination of the other two.

But switch is open, so:
- The right branch (with switch) is open
- Only the left branch (with bulb) is active

So:
- Current goes: battery → top bulb → middle bulb → back to battery
- So top and middle bulbs are in series → both on
- Right bulb is in parallel with switch → switch open → no current → off

> Answer:
- Top bulb: on
- Middle bulb: on
- Right bulb: off

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Final Answers (Summarized):

| Circuit | Bulb States |
|--------|-------------|
| Example | on, off, on |
| 1 (Top right) | both on |
| 2 (Second row left) | both on |
| 3 (Second row right) | A:on, B:on, C:off |
| 4 (Third row left) | both off |
| 5 (Third row right) | all off |
| 6 (Fourth row left) | both on |
| 7 (Fourth row right) | all off |
| 8 (Fifth row left) | both on |
| 9 (Fifth row right) | top:on, bottom:off |
| 10 (Sixth row left) | left:on, middle:on, right:off |
| 11 (Sixth row right) | top:on, middle:on, right:off |

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✔ Final Output Format (as per instruction):

Write "on" or "off" next to each bulb.

Since you can't edit the image, here's how to label them:

1. Top right (two bulbs in parallel):
- Both bulbs → on

2. Second row left (two in series):
- Both bulbs → on

3. Second row right (A, B, C):
- A: on
- B: on
- C: off

4. Third row left (two in parallel, switch open):
- Both bulbs → off

5. Third row right (three in parallel, switch open):
- All bulbs → off

6. Fourth row left (two in series, switch closed):
- Both bulbs → on

7. Fourth row right (three in parallel, all switches open):
- All bulbs → off

8. Fifth row left (two in series, switch closed):
- Both bulbs → on

9. Fifth row right (two in parallel, one switch open):
- Top bulb: on
- Bottom bulb: off

10. Sixth row left (three in parallel, one switch open):
- Left bulb: on
- Middle bulb: on
- Right bulb: off

11. Sixth row right (top, middle, right):
- Top bulb: on
- Middle bulb: on
- Right bulb: off

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Let me know if you'd like a visual version or want to mark them on the image!