Heat Transfer

Date: 2015-10-07; view: 508.

Answer the following question and read the text below to check your answer.

READING TASK: Text 2

Adjective Adverbs

Verbs and verbal phrases

Nouns and noun phrases

Give Russian equivalents of the following words and phrases. Try to memorize them.

ACTIVE VOCABULARY

Make all types of questions to the underlined sentence in exercise 14.

GRAMMAR FOCUS

Do you remember the ways of heat transfer from the course of physics?

Here are three easy things to know about the way heat flows:

1) There has to be a temperature difference. Energy only flows as heat if there is a temperature difference.

2) Energy as heat flows from a higher temperature to a lower temperature.

3) The greater or larger the difference in temperature, the faster the energy flows.

Heat can be transferred from place to place by conduction [conduction: The transfer of heat energy through a material - without the material itself moving. ], convection [convection: The transfer of heat energy through a moving liquid or gas. ] and radiation [infrared radiation: Electromagnetic radiation emitted from a hot object. ]. Conduction and convection involve particles, but radiation involves electromagnetic waves.Dark matt surfaces are better at absorbing heat energy than light shiny surfaces. Heat energy can be lost from homes in many different ways and there are ways of reducing these heat losses.

Conduction

Heat energy can move through a substance by conduction. Metals are good conductors of heat, but non-metals and gases are usually poor conductors of heat. Poor conductors of heat are called insulators. Heat energy is conducted from the hot end of an object to the cold end.

The electrons in piece of metal can leave their atoms and move about in the metal as free electrons. The parts of the metal atoms left behind are now charged metal ions. The ions are packed closely together and they vibrate continually. The hotter the metal, the more kinetic energy these vibrations have. This kinetic energy is transferred from hot parts of the metal to cooler parts by the free electrons. These move through the structure of the metal, colliding with ions as they go.