The fascinating scientific experiment will help to explain to children as the microwave warms products what aggregate states are accepted by water and what impact microwaves on ice make.
It is required to you
- - 2 plastic cups;
- - usual water;
- - microwave oven.
Instruction
1. Take a plastic cup, fill it with water and put in the freezer. In order that water in a glass for certain froze completely, it is better to leave it in the freezer at least for day.
2. Explain to children principle of work of the microwave oven: products are warmed because under the influence of microwaves of a molecule of water and food begin to move and rotate with a huge speed round its pivot-center. During this movement of a molecule continuously face with each other and rub among themselves. As a result of this friction heat which warms products is generated.
3. Show to children glasses with water and ice. Ask: what will be if to put both glasses in the microwave for 2 minutes? Most likely, children will tell that water in both glasses will heat up approximately equally. Listen to all assumptions which will be stated by children.
4. Put both glasses in the microwave oven and turn on it for 2 minutes at the maximum power.
5. When the microwave is switched-off, get glasses and put them on a table before children. It will turn out that ice did not thaw at all while in other glass water practically began to boil. Ask children why, according to them, so occurred.
6. Tell children that water has several aggregate states: firm, liquid and gaseous. At the same time in liquid and gaseous state of a molecule are in a free state, and under the influence of microwaves begin to move very quickly. In a firm state water forms crystals in which molecules are recorded strictly, almost not movably. When ice is affected by microwaves, molecules in it only slightly vibrate, are shaken, without creating the friction sufficient in order that ice significantly heated up.
7. Remind children that in the microwave it is possible to defreeze products. Ask: why the microwave oven could not melt ice, but at the same time she manages to cope with the frozen products? Having listened to assumptions of children, explain to them that the defrosting occurs because microwaves warm air in the oven. When hot air and steam defreeze the top layer of products, molecules are exempted from the ice fetters and begin to move quickly, heating up. At the same time heat is transferred deep into the frozen product, and gradually the piece is defrozen completely. If to leave a glass with ice in the microwave oven for longer time, ice in it will thaw too.