Practical No. 12: Determination of the rate of heat loss due to convection by Newton’s law of cooling.
XIV. Conclusions and Recommendations
- It is concluded that the rate of cooling of a body is directly proportional to the temperature difference between the body and its surroundings.
- It is recommended to use a double-walled enclosure to minimize heat loss due to radiation and drafts, ensuring the cooling is primarily due to convection.
XV. Practical Related Questions & Answers
Q1. State the Newton’s law of cooling.
- Answer: Newton’s Law of Cooling states that the rate of loss of heat of a body is directly proportional to the difference in temperature between the body and its surroundings, provided the temperature difference is small.
Q2. Name the three modes of transfer of heat.
- Answer: The three modes of heat transfer are:
- Conduction
- Convection
- Radiation
Q3. What is convection?
- Answer: Convection is the mode of heat transfer in fluids (liquids and gases) by the actual movement of the heated matter from one place to another.
Q4. Write the examples of radiation.
- Answer:
- Example 1: Heat from the sun reaching the earth.
- Example 2: Heat felt from a campfire.
Q5. Thermos is the example of which mode of transfer of heat?
- Answer: A thermos flask is designed to minimize heat transfer by all three modes.
- It has a vacuum to prevent conduction and convection.
- Its walls are silvered to minimize heat loss by radiation.
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