C10 | 열전달과 그 효과 (Transfer of Heat Energy & Its Effects)

Question 1

What is temperature and the SI Unit?

Answer 1

• The degree of hotness or coldness of an object is measured by the object’s temperature.
• Système International d’Unités = Kelvin (K)

Question 2

When a substance is heated, it undergoes __________ and ____________________

Answer 2

When a substance is heated, it undergoes expansion and increases in volume.

Question 3

When a substance is cooled, it undergoes __________ and ____________________

Answer 3

When a substance is cooled, it undergoes contraction and decreases in volume.

Question 4

When we pour boiling water too quickly into a cup made of thick glass, the glass sometimes cracks. Why?

Answer 4

The glass on the inside expands more quickly than the outside when heated. Thus, the walls of glass containers for hot liquids are usually thin.

Question 5

What are the three types of heat transfer?

Answer 5

Conduction
Convection
Radiation

Question 6

What is Conduction?

Answer 6

• Conduction is the process of heat transfer through a medium or material without any movement of the medium or material.
• A material that conducts heat is a conductor.
• Poor conductors of heat are called insulators.

Question 7

What is Convection?

Answer 7

• Convection is the transfer of heat from one place to another by the movement of fluids (liquids and gases).
• Solids are better conductors of heat than liquids and gases. Liquids and gases transfer heat through the process of convection.
• Convection takes place due to the expansion of a fluid. When it is hot, its volume increases and its density decreases.
• The less dense fluid then rises while the denser fluid flows in to take its place.

Question 8

What is Radiation?

Answer 8

• Radiation is the transfer of heat, in the form of waves, from one place to another. It does not require a medium for transmission.
• Radiation is a method of heat transfer that does not need the presence of matter.
  – This means that heat can radiate across empty space or a vacuum.
• For example, heat from the sun radiates across millions of kilometres of empty space to reach earth.

Question 9

The ____ and ____ the surface, the higher the rate of radiation or absorption.

Hint: Colour, Texture

Answer 9

The blacker and rougher the surface, the higher the rate of radiation or absorption.

A dark and rough surface is a good radiator and absorber of heat.

Question 10

The ____ the area, the ____ the rate
of radiation or absorption.

Hint: Size of Area, Speed of Radiation/Absorption

Answer 10

The greater the area, the faster the rate of radiation or absorption.

The pipes of a radiator have a large surface area from which heat is radiated.

Question 11

The ____ the body, the ____ rate of radiation.

HInt: Temperature, Rate of Radiation

Answer 11

The hotter the body, the faster the rate of radiation.

Lava radiates heat at a very high rate because of its high temperature.