Heat Transfer Flashcards
The 3 heat transfers
Conduction, radiation, convection
Poor conductors are
Plastic, wood
Conduction :How do pans heat up on a hob and oven
Atoms in metal vibrate as heat transfers from the hob or heat up the metal in the oven. The metal heats and passes heat to the food.
Convection :How does water heat a pan
Heat is conducted through the metal pans to the water molecules. Water molecules, circle passing the heat energy onto the food.
The more heat energy….
The faster the water molecules move
Radiation: grilling or barbecuing
Infrared rays heat the food surface and absorbed. Food must be thin (less than 3.5) or will not cook through.
How thin must the meat be for radiation
Less than 3.5cm thick
What radiation does a microwave use
Microwaves the travel in straight lines to penetrate food.
What are microwave hot spots
Hot spots can occur so should stir and left to allow heat to distribute evenly.
Conduction summary
Heat transferred through directly contact. The heat passes from one particle to another.
Examples of conduction
Frying , slow cooking, cooking food in a pan or stove, frying eggs, grilling sandwiches.
Convection summary
Heat is transferred by movement of liquids. (Liquids or gases)
Convection boiling water
Heat moves through water as it heats up
Convection in an oven
Hot air, circulates around the food, cooking evenly
Convection examples
Boiling, roasting
