In How to know, about science and technology series we will provide you information about science and technology, We are in making part of series and every part will contain 8-10 scientific questions and answer !
HOW DOES A REFRIGERATOR WORK?
In the sides of a refrigerator there are pipes that contain a cold fluid. This makes the inside of the refrigerator cold. The cold fluid is pumped through the pipes to carry heat away from the food in the refrigerator and keep it cold.
The fluid that circulates in the pipes of the refrigerator easily changes from a liquid to a vapour. As it enters the interior, it is liquid and is pumped through an evaporator. This lowers its pressure and it becomes vapour. The change from liquid to vapour makes the vapour cold because it takes up heat.
HOW DOES A MICROWAVE OVEN WORK?
A microwave oven does not have burning flames or red-hot plates like gas and electric cookers. You put the food into a metal box and press a switch. Inside the box, invisible energy rays bombard the food and cook it very quickly.
A microwave oven gets its name from the rays that cook the food, which are called microwaves. They are like radio waves, and the rays heat up objects in the same way as the Sun’s rays warm us.
HOW DO VACUUM FLASKS KEEP THINGS HOT?
A vacuum flask can keep drinks hot for several hours. This is because the flask stops as much heat escaping
from the drink as possible. As the drink loses very little heat, it keeps hot for a long time.
A vacuum flask is designed to prevent heat loss in several ways. The silver walls of the container inside the flask reflect heat rays back into the container. In addition, there is a vacuum between the walls of the container to stop heat flowing through the walls.
HOW DOES A PRESSURE COOKER WORK?
A Pressure cooker is like a large saucepan with a tight-fitting lid. A little water is put in the cooker with the food. When the cooker is heated, the water boils and produces steam inside the cooker. This steam makes the food cook very quickly.
The reason that food cooks quickly inside a pressure cooker is that it gets very hot. When the water boils inside the cooker, the steam that is produced cannot get out. It builds up a high pressure inside the cooker.
HOW DO BUBBLES GET INTO FIZZY DRINKS?
When you open a fizzy drink, A bubbles form inside the drink. These are bubbles of a gas called carbon dioxide, and help to make the drink taste sharp. The gas is dissolved in the drink when it is made at the factory.
At the factory, carbon dioxide gas is forced into the drink under pressure so that it dissolves in the liquid. The drink remains under pressure in the bottle or can so that the gas stays dissolved in the drink. However, when the bottle or can is opened, the pressure is released. This is why the drink hisses as it is opened.
WHAT IS BREAD MADE OF?
Bread is made from wheat or rye, A which is ground into flour. Then the flour is mixed with yeast, water, sugar and salt to make dough. The dough is cut into blocks which are then baked in an oven to make loaves of bread.
Dough is made by mixing flour yeast, water, sugar and salt and then allowing this mixture to ferment. The yeast causes the dough to rise by forming bubbles of carbon dioxide gas in the dough. The heat kills the yeast so that the bread sets in a loaf shape. The crust forms and the bread is cooked.
HOW IS FOOD PACKED IN CANS?
Food that is packed in cans stays fresh because air and germs are removed from inside the cans. A can has no lid when it is filled with food. Air and germs are removed, and the lid is sealed to make it airtight. This is done in a canning factory.
The food that is stored in cans has to be made sterile and free from germs to keep it fresh. In a canning factory, the food is placed in the cans, with a liquid such as sauce or syrup. Air is removed and the lids are sealed onto the cans. The cans are then heated to sterilize the food inside.
HOW DO LOCKS WORK?
When a door is locked, a bolt or bar moves out of the lock and fits into a slot in the door frame. Unlocking the door slides the bolt back. When the key is put into the lock, it frees the bolt so that it can move. Turning the key then moves the bolt.
In a cylinder lock, the centre of the lock turns. The key raises a set of pins that normally hold the centre fixed to the rest of the lock so that it cannot move.
A lever-tumbler lock contains a set of levers that hold the bolt closed or open. Springs keep the levers in position so that the bolt cannot move.
Also Read –
- Science And Technology Question & Answer – Part 2
- Science And Technology Question & Answer – Part 3
- Science And Technology Question & Answer – Part 4
- Science And Technology Question & Answer – Part 5
- Science And Technology Question & Answer – Part 6
- Science And Technology Question & Answer – Part 7
- Science And Technology Question & Answer – Part 8
- Science And Technology Question & Answer – Part 9
- Science And Technology Question & Answer – Part 10
- Science And Technology Question & Answer – Part 11
- Science And Technology Question & Answer – Part 12