Question

Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will get heated in a shorter time?

Answer 1

Hint: The part of the candle which has a higher temperature will give a high amount of heat to the beaker when kept in vicinity. In candles, the temperature is lower at the wick in comparison to the upper part of the yellow flame.

Complete answer:
Here, both Abida and Ramesh are heating the water in a beaker but the contact of the beaker with the flame of the candle is different in both the cases. So, the water in the beakers will get different amounts of heat energy transferred and thus both of them will take different amounts of time to get water boiling.
- Let’s know about the so-called temperature zones in the flame of a candle.
- Near the wick in the yellow zone in a flame of candle, the temperature is found to be the lowest around the flame. So, if we keep a beaker near the wick, the temperature there will not be as high (around 1000$^{\circ }C$) and as a result heat transfer will also be lower. Due to this, water will take more time to get enough heat to attain required temperature. So, in the case of Abida, it will take more time to heat the water in the beaker.
- Ramesh has kept the beaker at the outermost part of the flame. This part of the flame is not luminous means it is not yellow in colour but has the highest temperature. The temperature in this part is around 1400$^{\circ }C$. Thus, in this case the heat transfer will be higher and water will get heated in a shorter period of time.
Therefore we can conclude that Ramesh will heat the water faster than Abida.

Note:
Colour of the flame does not suggest the temperature of the flame. Actually, different materials on combustion can give different coloured flames. Remember that the blue zone in the flame of the candle has relatively lower temperature than the yellow part.