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Heat – Good And Poor Conductors Of Heat
In this article, you will be introduced to the concept of good and poor conductors of heat based on the Singapore Primary 4 Science Syllabus. We will focus on the following two main aspects:
- Examples of good and poor conductors of heat
- Uses of good and poor conductors of heat
Good And Poor Conductors Of Heat
Good conductors of heat are objects that allow heat to flow through them easily. Metals are materials that are good conductors of heat because they allow heat to pass through them quickly.
On the other hand, objects that do not allow heat to flow through them easily are known as poor conductors of heat. Some examples of poor conductors of heat include materials like wood, rubber and plastic. Air is also considered a poor conductor of heat.
Uses Of Good And Poor Conductors Of Heat
Cooking Pot
Let us take a look at the materials used to make the different parts of a cooking pot.
Image Credits: icons8
Body: The body of the cooking pot is made of metal which is a good conductor of heat. This allows heat to be conducted from the flame to the food more quickly so that the food can be cooked faster.
Handles: The handles of the cooking pot are made of plastic which is a poor conductor of heat. This ensures that the handles do not heat up easily, making it easier for us to hold the pot by the handles without burning ourselves.
Winter Jacket
Now, let us examine how a winter jacket keeps us warm even during the cold winter.
Image Credits: bigbarbs
A winter jacket is made of fabric that is a poor conductor of heat. On top of that, the jacket can trap air around our body. Being poor conductors of heat, air and fabric both help to slow down heat loss from our body to the cold surroundings, allowing us to stay warm in winter.
Conclusion
In this article, we looked at examples of good and poor conductors of heat. We have also examined how good and poor conductors of heat can be used to make different objects around us.
Test Your Concepts
Answer the following questions based on the concepts that we have covered in this article. If you are unclear, you may want to revisit the relevant section to revise the concepts.
Question 1:
Alison was about to start baking when she noticed that the material used to make oven gloves had small air spaces inside it.
Explain how the air spaces in the material would help protect Alison’s hands from hot objects.
Solution:
Air is a poor conductor of heat and would slow down heat transfer from hot objects to Alison’s hands.
Explanation:
Air, being a poor conductor of heat, is often being trapped in apparels that we wear to slow down heat transfer to / from our body.
Question 2:
Rachael had a rod made of two different materials, steel and wood. She attached four pins onto the rod with some wax and heated the rod at the centre.
Rachael observed that pin \(\text{B}\) fell off the rod first, followed by pin \(\text{A}\), pin \(\text{C}\) and then pin \(\text{D}\).
Write down two conclusions that Rachael could make based on her observations.
Solution:
Steel is a better conductor of heat than wood.
The wax nearer to the flame is heated up more quickly than a piece of wax further away from the flame.
Explanation:
Pin \(\text{B}\) fell off before Pin \(\text{C}\), showing that steel is a better conductor of heat than wood.
Pin \(\text{B}\) fell off before Pin \(\text{A}\), showing that heat is conducted to the wax nearer to the flame faster.
Test Yourself
Mrs Tan wants to buy a frying pan which is able to conduct heat quickly. She also wants to buy one which she can hold without burning her hand.
Which materials should parts X and Y of the frying pan be made of?
| X | Y | |
|---|---|---|
| (1) | Steel | Plastic |
| (2) | Iron | Steel |
| (3) | Ceramic | Copper |
| (4) | Copper | Iron |
Part X should be made of a material that is a good conductor of heat so that the food will be well cooked.
Part Y should be made of a material that is a poor conductor of heat so that she is able to hold the pan without getting burnt.
The diagram below shows a metal kettle.
Which one of the following materials and its stated property is most suitable to make Part Y?
1. Plastic should be used because it is lightweight.
2. Metal should be used because it is a good conductor of heat.
3. Metal should be used because it is more durable than plastic.
4. Plastic should be used because it is a poor conductor of heat.
Part Y is the handle of the kettle and should be made of a poor conductor of heat such as plastic to protect our hands from the heat of the hot kettle.
Some houses in other countries are designed to withstand low temperatures during long winters. One such characteristic is shown below.
How does the double-layered glass window help to conserve heat during winter?
1. The two layers of glass make it stronger.
2. The air in the gap acts as a poor conductor of heat.
3. The gap allows contraction of glass when it is cold.
4. The gap allows expansion of glass when it is heated.
As air is a poor conductor of heat, heat in the house is lost slowly to the colder outside surroundings, thus conserving heat inside the house.
Look at the diagram below. Nails A, B and C are attached to the metal rod by wax.
Nail A is the last one to fall because __________.
1. heat travels from X to Y
2. heat travels from Y to X
3. heat is lost from X to Y
4. heat is gained from X to Y
Heat flows from a hotter to a colder place.
As the heat flows along the metal rod, the wax will melt off, allowing the nails to drop off one by one.
Nail C would drop off first, followed by B, then A.
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