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The question asks to calculate the electric energy consumed by a light bulb with the following specifications:
- Rated voltage: 220V
- Rated power: 100W
- Actual operating voltage: 110V
- Operating time: 5 hours

To solve this problem, we need to find how much energy is consumed under these conditions.

### Step 1: Adjust the Power for the Given Voltage
The power consumed by the bulb depends on the operating voltage. The relation between power and voltage is:

\[
P = P_{\text{rated}} \times \left( \frac{V_{\text{actual}}}{V_{\text{rated}}} \right)^2
\]

Given:
- \( P_{\text{rated}} = 100W \)
- \( V_{\text{actual}} = 110V \)
- \( V_{\text{rated}} = 220V \)

Substitute the values into the formula:

\[
P = 100W \times \left( \frac{110}{220} \right)^2 = 100W \times \left( \frac{1}{2} \right)^2 = 100W \times \frac{1}{4} = 25W
\]

So, the bulb operates at 25 watts under 110V.

### Step 2: Calculate Energy Consumption
Energy consumption is given by:

\[
E = P \times t
\]

Where:
- \( P = 25W \) (calculated power)
- \( t = 5 \text{ hours} \)

\[
E = 25W \times 5 \text{ hours} = 125 \text{ Wh} = 0.125 \text{ kWh}
\]

### Conclusion:
The energy consumed by the bulb in 5 hours is **0.125 kWh**.

The correct answer is **D (0.125 kWh)**.

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Would you like more details, or do you have any questions? Here are five related questions:

1. How is the power consumption of an electrical device affected by voltage changes?
2. What is the difference between power (W) and energy (Wh or kWh)?
3. How do you convert energy from joules (J) to kilowatt-hours (kWh)?
4. How would the energy consumption change if the operating time was doubled?
5. What would happen if the voltage supplied to the bulb exceeded its rated voltage?

**Tip**: To prevent overloading, it's important to supply devices with their rated voltage. Too high or low a voltage can damage the device or cause it to operate inefficiently.

Một bóng đèn có ghi 220V - 100W hoạt động liên tục trong 5 giờ với hiệu điện thế 110V. Điện năng tiêu thụ trong thời gian đó là:

Learn how to calculate the energy consumption of a 100W light bulb rated for 220V operating at 110V for 5 hours. This example demonstrates key concepts in power, energy, and voltage, using formulas for energy consumption and power adjustment. Suitable for Grades 10-12 physics students.

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