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 RADAR WORK?
Radar is a way of finding out how far away things are. A radar antenna sends out signals like radio signals. These bounce off a distant object and come back to the antenna. The radar set works out how far away the object is by measuring the time it takes for the signal to return.
Radar helps to guide ships and aircraft, especially at night and in fog. The radar sets can detect other ships and aircraft as well as the shore or the land below.
HOW DOES SONAR WORK?
Sonar is used on boats and ships to A find the depth of anything beneath them. Sonar can measure the depth of the sea bed as well as locate shoals of fish and submarines. It works like radar, except that sonar uses sound signals instead of radio signals.
Sonar is also used to detect enemy submarines.
HOW DOES A THERMOMETER WORK?
Inside a thermometer is a very A narrow glass tube, At the bottom is a bulb containing a liquid. When the thermometer gets warm, the liquid expands and forces some of the liquid up the tube to a certain level. If it gets colder, the liquid contracts and falls.
The silver liquid mercury, in the bulb of a thermometer expands and contracts as the vibration of its atoms or molecules increases and decreases. Mercury expands more quickly, so it shows the temperature faster.
HOW DO EXPLOSIVES WORK?
When an explosive goes off, the chemicals in the explosive suddenly produce lots of gas and heat. The hot gases expand in size very quickly. This gives the explosion its force and makes a wave of high pressure move out through the air.
High explosives like gelignite produce large amounts of hot gas very quickly to give a powerful instant explosion. The chemical reaction that occurs moves through the explosive at speeds of up to 7.5
kilometres a second.
High explosives are set off with detonators.
HOW DOES A RIFLE WORK?
Pulling the trigger of a rifle releases a spring. This makes a firing pin strike the base of a cartridge. The cartridge contains explosive and a bullet. The firing pin sets off the explosive, and the gas produced by the explosion makes the bullet fly out the rifle.
In the cap of the cartridge is a primer that detonates to set off the charge of propellant in the cartridge case. Spiral grooves around the inside of the barrel cause the bullet to spin as it leaves the rifle.
Automatic rifles contain a chamber of cartridges called a magazine.
HOW DOES THE NIGHT-SIGHT ON A GUN WORK?
Marksmen can see a target even at A night. This is because there is always a little light even if it looks totally dark. The night-sight picks up this light from the target and makes an image of it appear on a small screen.
At the front of the night-sight is a lens. It focuses the very weak light rays coming from the target onto a metal disc called a photo-emitter. This disc produces electrons. The electrons travel down the tube of the night-sight, and are focused into a beam by magnets. The beam strikes a fluorescent screen, causing it to light up with an image of the target.
HOW DOES AN ATOMIC BOMB WORK?
An atomic bomb makes a huge explosion powerful enough to destroy a city. It contains pieces of uranium or plutonium instead of ordinary explosive. When the bomb is dropped, the pieces are fired together inside the bomb and it explodes.
When the pieces of uranium or plutonium meet, the nuclei of the atoms begin to break apart. A nuclear chain reaction occurs like that in a nuclear reactor.
HOW DOES A MISSILE GET TO ITS TARGET?
A missile is a rocket with an explosive A warhead. When the missile reaches its target the warhead explodes, The missile may chase the target if it is moving. The guidance system in the missile detects heat coming from its engine or uses radar. Other missiles are guided from the ground.
A radar system may track both the missile and its target. A computer reads the radar signals and controls the missile’s guidance system to guide it to the target by radio.
WHAT IS A SOLID?
A solid is a substance or a material A that does not flow. Solids include ice, steel, wood, paper, cloth, salt and sugar. A piece of a solid may bend, stretch or contract in size, but it does not otherwise change its shape.
A solid is made of atoms or molecules that are arranged in rows or patterns. The atoms or molecules are pulled together by forces between them. If the forces are strong, then the solid is hard and tough. If they are weak, then the solid is soft or may break easily.
Also Read –
- Science And Technology Question & Answer – Part 1
- 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 12