Heat Transfer - Convection

Question 1

where and how does convection take place

Answer 1

• takes place in gases and liquids
• when liquids and gases are heated, their molecules vibrate according to the heat applied. the density of the liquid or gas is reduced, and the molecules move in currents (heat liquids/gas rise and cold liquid/gas sink) until it has the same temperature all over

Question 2

example of foods with slow convection currents

Answer 2

cake batters and thick sauces

Question 3

an example of something heated by convection currents and how

Answer 3

• ovens are heated by convection currents
• the element fitted at the bottom of the over heats the lower layer of air; this becomes less dense and rises. colder air is heavier and flows to the bottom and is in turn heated. thus, convection currents are formed. thermofan ovens promote an even spread of heat

Question 4

example of something cooled by convection currents

Answer 4

refrigerators are cooled by convection currents

Question 5

methods of cooking which use convection currents to heat food

Answer 5

• boiling
• deep frying
• baking in the oven