Heat Conduction #2

Question 1

What state does conduction mainly occur in?

Answer 1

Solids

Question 2

Define ‘conduction of heat energy’

Answer 2

Conduction of heat energy

The process where VIBRATING PARTICLES pass on their EXTRA KINETIC ENERGY to their NEIGHBOURING PARTICLES

Question 3

Describe how the heat radiatiing from the surface of a solid is increased through conduction, when a heat source is applied to the solid

(5)

Answer 3

1. A heat source causes the particles in the solid next to the source to vibrate more
2. These vibrating particles transfer their extra kinetic energy to their neighbouring particles by collision
3. This process continues throughout the solid
4. Gradually some of the extra kinetic energy (or heat) is passed all the way through the solid
5. This causes a rise in temperature on the opposite side of the solid.

Question 4

How is the rate of conduction affected by the density of the solid?

Why?

Answer 4

Usually, the denser the solid, the faster the rate of conduction

This is because the particles are closer together, and will collide more often transferring more energy between them

Question 5

Describe the particle structure of insulators, and how this affects their rate of conduction

Answer 5

Thye have larger spaces between their particles (than conductors), meaning that particles collide less often, thus transferring less energy between them in a given time.

This means they conduct heat energy much more slowly

Question 6

Why are metals good conductors?

Answer 6

Because of their free electrons!

Question 7

Describe how heat energy is transferred through a metal

(3)

Answer 7

1. At the hot end of the metal the electrons move faster, and collide with other free electrons, transferring energy
2. The electrons can move through the metal, colliding with ions as they go
3. This speeds up conduction, as the electrons can move their energy to the other end of the metal more quickly than fixed particles because they are free to move all through the metal

Question 8

Is conduction faster through a long, thin rod, or a short, fat rod?

Why?

Answer 8

Through the short fat rod

Because the electrons have less far to travel

Question 9

Describe why a metal spade feels hotter than a wooden handle on a hot day, even when they are the same temperature

Answer 9

The metal is a better conductor, so the conducts the heat more quickly into your skin, so your skin heats up quicker

Question 10

Describe why a metal spade feels colder than a wooden handle on a cold day, even when they are the same temperature

Answer 10

The metal is a better conductor, so the conducts the heat more quickly out of your skin, so your skin cools down quicker

Question 11

Energy is transferred through the metal walls of a drink can by conduction

Explain how

Answer 11

The free electrons in the metal

Gain kinetic energy

and the electrons transfer this kinetic energy to other electrons and atoms and ions ^{(<strong><u>NOT particles</u></strong>)}

by collision