Explain the principle involved in the usage of hot water bottles to warm beds in cold countries.

Explanation

**Step-by-Step Solution:**

1. **Understanding Hot Water Bottles**: Hot water bottles are containers filled with hot water, which are used to provide warmth, especially in cold weather.

2. **Principle of Specific Heat Capacity**: The principle behind the effectiveness of hot water bottles lies in the concept of specific heat capacity. Specific heat capacity is the amount of heat energy required to raise the temperature of a substance.

3. **High Specific Heat of Water**: Water has a high specific heat capacity, which means it can absorb a large amount of heat without changing its temperature significantly. This property allows water to retain heat for a longer period.

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