Category How does It works, How things work, How is it done, Curiosity

You are building a road but a mountain is in the way. Could the road be built over the mountain? That would be rough travelling. What about going around? That would take longer-to build it and to drive on it. What about digging a tunnel? A tunnel is the shortest route, and there are many ways to build one.

Tunnels built through hard rock are usually blasted. Workers use explosives to blast each section of rock. Then they build supports in the newly opened part of the tunnel to keep rock from falling in.

Huge boring machines tunnel through clay or soft rock. As steel tubes dig through the ground, the machine “swallows” the earth and rock. The earth is dumped at the back of the machine the tunnel opening where trucks can haul it away. Reinforced concrete or steel is used to make the floor, walls, and roof of the tunnel.

Cut-and-cover tunnels are built close to the surface. Workers dig a deep trench. Then they build a floor, walls, and roof of reinforced concrete. When the concrete has hardened, the area around the concrete is filled to street level.

The mountain is no longer in the way. You simply drive right through it.

Picture Credit : Google

Aeroplanes get into traffic jams just in the same way cars do-especially around busy airports. But people called air traffic controllers know where each plane is located. They use radar to help them direct air traffic.

Radar allows the controllers to find planes that are too far away to see. And radar does this at night and in rain, fog, or snow.

A radar set sends out radio waves. When the radio waves hit a flying plane, or even a raindrop, they bounce back to the radar set. This makes spots of light appear on the tracking screen.

The moving spots of light tell a controller where the object is. They know how far away it is, how high it is, how fast it is moving, and which way it is going. Then the controllers can direct the air traffic, much as police officers direct road traffic. They make sure each plane follows a safe path when flying, taking off, or landing.

The planes have radar sets, too. The pilot can look at the radar to make sure that no violent storms or other planes are dangerously close.

Picture Credit : Google

Have you ever tried to switch channels on TV when someone stood in the way? Nothing happened. Why not? The transmission of the signal was blocked. The signal from the remote control hit someone’s body instead of the TV.

Remote means “far away”. When you use the remote control, you are controlling the TV from a distance. The remote control uses an invisible type of light called infrared light to send a signal to a receiver on the TV.

The buttons on your remote control send different codes to the TV. The code consists of long and short flashes of infrared light. When you press a button, the remote control sends the code for that button to the receiver in the TV. The TV “sees” the signal and carries out the command.

Some toy cars use a radio remote control to guide their movements. Turning knobs or moving levers sends a signal to the car to go forwards or backwards, or turn left or right. A garage door opener uses a radio wave to send its signal. Different openers have different frequencies so that you won’t open your neighbour’s garage door by mistake.

Picture Credit : Google

Did you know that the pictures on TV are a jumble of red, green, and blue dots? When you sit across the room, the dots blend into the images you see.

At the television station, a camera records the picture and sound from the scene you are watching. Mirrors in the camera split light from the scene into red, green, and blue. A tube in the camera changes the light to radio signals. The television station broadcasts the programme to your home.

TV antenna, cable, or satellite dish A receives many broadcast signals at once. The television tuner is used to select the signal for the TV channel you want to see. The tuner passes this signal to the amplifier. The amplifier separates the sound from the pictures.

The sound goes to the speakers. The picture signal is sent to a decoder. The decoder sends the signal to the electron guns. There is one gun for each colour red, blue, and green. The electron guns zip across the screen in weak or strong bursts of light. These bursts form the picture you see on the screen.

Picture Credit : Google

Radio signals are heard almost everywhere. But how does a radio work? The radio transmitter (where the sounds come from) changes sound waves into electrical signals. It sends them through the air as radio waves. The radio waves that leave the transmitter have different frequencies for each station. Frequencies are the number of times the waves vibrate per second.

You tune your radio by choosing a number on the controls. Each number represents a frequency. So if you always tune in the same frequency, you always pick up the same station.

When you tune in a station, signals are picked up by the radio. These signals are sent to an electromagnet in the radio speaker. The electromagnet makes a cone on the speaker vibrate. These vibrations are the sounds you hear on your radio. They sound exactly like the sounds made at the transmitter-voices, music, or even the squeak of a mouse.

An Italian inventor, Guglielmo Marconi, realized that coded messages could be sent over long distances without using wires. Because the transmitter and receivers did not need wires, the process was called wireless telegraphy. This discovery led to present-day radio.

Picture Credit : Google

Many people work M together to design a new car.

First, drawings are made with a computer. This is called computer aided design, or CAD. Computers are used to create, test, and change the plans. This saves time and money. Next, artists may make a clay model of the car. The clay is coated with shiny film. It looks like a real car.

Other artists create the inside of the car. They design the seats. They decide where the controls will be. They plan everything from turning signals and seat belts to airbags and drink holders.

Finally, a fibreglass model of the car is built. It has real tyres, glass windows, and trim. This final model looks exactly like the new car will look.

Product engineers plan how each part of the car will be made. They use a computer that traces every line and curve on the final model. Factories make the parts and a completed car is made and tested.

Next, parts are shipped to several factories to be assembled. Each worker in the assembly line adds a different part. At the end, a complete car rolls off the line.

Picture Credit : Google