Hey there, curious researcher friend Lara Obaid! I'll do my best to provide some insights into your question.

The power consumption of a heating mantle can indeed vary depending on the amount of water you're heating. Heating mantles are designed to maintain a consistent temperature, so they will adjust the amount of power they use to achieve this goal. Here's why the power consumption may differ:

1. **Heat Capacity**: The amount of water you're heating directly affects the heat capacity of the system. More water requires more energy to raise its temperature to the desired level.

2. **Rate of Heating**: When you initially start heating the water, it will absorb heat at a faster rate because there's more of it. As it gets closer to the desired temperature, the rate of heating may slow down, and the heating mantle might reduce its power output.

3. **Maintaining Temperature**: Once the water reaches the desired temperature, the heating mantle will continue to use power to maintain that temperature. Here, the power consumption might not vary significantly between 1000 ml and 1400 ml of water if the set temperature is the same.

4. **Efficiency**: The efficiency of the heating mantle can also impact power consumption. More efficient mantles might use slightly less power to achieve the same temperature for a given volume of water.

So, while the power consumption may differ during the heating phase, it should even out once the water reaches and maintains the desired temperature. Keep in mind that the exact power usage can vary between different heating mantles, so you Lara Obaid might notice some variation based on the specific model you're using.

Remember to always follow the manufacturer's guidelines and safety instructions when using heating equipment, and consider factors like the rate of heating, insulation, and efficiency when comparing power consumption for different volumes of water.