Lesson 7 Part 1
Heat can travel through solids. If you heat one end of an iron rod, the other end will soon get hot. Heat energy quickly flows through the rod. The movement of heat through the solid metal is called conduction.
We often use cookware made of stainless steel or iron because such metals are good conductors of heat. When you cook, you will probably use a pan with a plastic or wooden handle. Like most other non-metals, wood and plastic don’t allow heat to flow easily through them. Substances like these are called insulators.
Air is also a good insulator. When you wear clothes made of wool, fur or feathers, the air trapped in them prevents your body heat from escaping. That’s why you can keep warm in such clothes.
We often use cookware made of stainless steel or iron because such metals are good conductors of heat. When you cook, you will probably use a pan with a plastic or wooden handle. Like most other non-metals, wood and plastic don’t allow heat to flow easily through them. Substances like these are called insulators.
Air is also a good insulator. When you wear clothes made of wool, fur or feathers, the air trapped in them prevents your body heat from escaping. That’s why you can keep warm in such clothes.
Lesson 7 Part 1-1
Heat can travel through solids.
Lesson 7 Part 1-2
If you heat one end of an iron rod, the other end will soon get hot.
Lesson 7 Part 1-3
Heat energy quickly flows through the rod.
Lesson 7 Part 1-4
The movement of heat through the solid metal is called conduction.
Lesson 7 Part 1-5
We often use cookware made of stainless steel or iron.
Lesson 7 Part 1-6
Because such metals are good conductors of heat.
Lesson 7 Part 1-7
When you cook, you will probably use a pan with a plastic or wooden handle.
Lesson 7 Part 1-8
Like most other non-metals, wood and plastic don’t allow heat to flow easily through them.
Lesson 7 Part 1-9
Substances like these are called insulators.
Lesson 7 Part 1-10
Air is also a good insulator.
Lesson 7 Part 1-11
When you wear clothes made of wool, fur or feathers, the air trapped in them prevents your body heat from escaping.
Lesson 7 Part 1-12
That’s why you can keep warm in such clothes.
Lesson 7 Part 2
Air is an insulator of heat. This means heat hardly travels through air by conduction. But if you turn on an electric heater, the room will be warmer. How does the air in the room get heated?
When the heater on the floor is on, the heater heats the air around it and the hot air rises and escapes from the top of the heater. Then the rising air makes the colder air sink to the bottom of the heater to be heated again. This makes the air in the room “flow.” This flow of heat is called a convection current. Thermal energy is transferred from hot places to cold places by convection.
Water in a kettle warms in the same way. In fact, convection is the main way for heat to travel through liquids and gases.
When the heater on the floor is on, the heater heats the air around it and the hot air rises and escapes from the top of the heater. Then the rising air makes the colder air sink to the bottom of the heater to be heated again. This makes the air in the room “flow.” This flow of heat is called a convection current. Thermal energy is transferred from hot places to cold places by convection.
Water in a kettle warms in the same way. In fact, convection is the main way for heat to travel through liquids and gases.
Lesson 7 Part 2-1
Air is an insulator of heat.
Lesson 7 Part 2-2
This means heat hardly travels through air by conduction.
Lesson 7 Part 2-3
But if you turn on an electric heater, the room will be warmer.
Lesson 7 Part 2-4
How does the air in the room get heated?
Lesson 7 Part 2-5
When the heater on the floor is on, the heater heats the air around it.
Lesson 7 Part 2-6
And the hot air rises and escapes from the top of the heater.
Lesson 7 Part 2-7
Then the rising air makes the colder air sink to the bottom of the heater to be heated again.
Lesson 7 Part 2-8
This makes the air in the room “flow.”
Lesson 7 Part 2-9
This flow of heat is called a convection current.
Lesson 7 Part 2-10
Thermal energy is transferred from hot places to cold places by convection.
Lesson 7 Part 2-11
Water in a kettle warms in the same way.
Lesson 7 Part 2-12
In fact, convection is the main way for heat to travel through liquids and gases.