Circuit Testing worksheet with diagrams to determine if bulbs will light.

Let’s analyze each circuit one by one to determine whether the bulb(s) will light up. For a bulb to light, there must be:

✔ A complete (closed) circuit from the positive terminal of the battery, through the bulb(s), and back to the negative terminal.

✔ At least one power source (battery).

✔ No open switches or broken paths.

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Top Row

1. Left Circuit:
- Battery + bulb connected in a loop.
- ✔ Complete circuit → Yes

2. Right Circuit:
- Two batteries and two bulbs — all connected in series in one loop.
- ✔ Complete circuit → Yes

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Second Row

3. Left Circuit:
- Only a bulb — no battery.
- ✘ No power source → No

4. Right Circuit:
- Battery + bulb + open switch (gap in the circuit).
- ✘ Open circuit → No

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Third Row

5. Left Circuit:
- Three batteries in series + one bulb → complete loop.
- ✔ Complete circuit → Yes

6. Right Circuit:
- Two batteries connected positive-to-positive and negative-to-negative — this is a short circuit or invalid connection. No current flows through the bulb because the batteries oppose or cancel each other (depending on interpretation), and more importantly, there’s no bulb in the circuit at all!
- Wait — actually, looking closely: there is no bulb shown in this diagram! Just two batteries connected directly.
- ✘ No bulb → No (even if there were a bulb, this wiring is incorrect, but since there's no bulb, definitely won't light)

> Correction: The diagram shows only two batteries connected end-to-end with no load (bulb). So even if we assume it's a mistake, technically no bulb = no light.

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Fourth Row

7. Left Circuit:
- Battery + open switch + bulb.
- ✘ Switch is open → No

8. Right Circuit:
- Battery + bulb + open switch (three dots = open switch).
- ✘ Open circuit → No

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Fifth Row

9. Left Circuit:
- Two bulbs connected in parallel, but no battery.
- ✘ No power source → No

10. Right Circuit:
- One battery + three bulbs: one in series with two in parallel.
- ✔ Complete circuit → Yes

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Sixth Row

11. Left Circuit:
- Battery + open switch + bulb.
- ✘ Open circuit → No

12. Right Circuit:
- Bulb + open switch — no battery.
- ✘ No power source → No

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## ✔ Final Answers:

| Circuit | Answer |
|---------|--------|
| 1 | Yes |
| 2 | Yes |
| 3 | No |
| 4 | No |
| 5 | Yes |
| 6 | No |
| 7 | No |
| 8 | No |
| 9 | No |
| 10 | Yes |
| 11 | No |
| 12 | No |

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## 📝 Summary Explanation:

- Bulbs light only when there’s a complete path for current, powered by a battery, with no open switches or missing components.
- Circuits without batteries → No light.
- Circuits with open switches → No light.
- Circuits with shorted or incorrectly wired batteries → usually No light (or dangerous, but not functional here).
- Parallel/series connections are fine as long as the circuit is closed and powered.

✔ You can now check the boxes accordingly on your worksheet!