How does Radar Work?
A radar system sends powerful pulses of radio waves and listens for any echoes. The radar analyzes the reflected signal and locates the object reflecting it, and sometimes radar is able to identify that object.
What drives a ship?
A ships engine turn the propeller, which has blades like a fan. As the blades turn they push the water back and the ship moves forward.Some special ships move without propellers . Examples include the hydrofoil which gets its power as water is forced out of a jet.
Hydro Power Station
A hydro-electric power station uses the force of moving water to make electricity.
First a dam is built to hold a deep lake of water. The lake is filled by streams of rivers flowing into it.
What is the Channel Tunnel?
The channel tunnel runs between England and France, and it was one of the greatest civil engineering projects of the 20th century. The tunnel is 49.4 km (30.7 miles) long, of which 38 km (23.6 miles) are under the sea. There are three tunnels, two for high-speed trains and a third for maintenance, ventilation and emergency services. Trains traveling up to 300 km per hour (186 miles per hour) link London and Paris in just three hours.
When will all our oil be used up?
We use coal, oil, gas and nuclear fuel to generate electricity. These fuels are primary energy sources but they are non-renewable. This means that once you’ve used them they cannot be replaced.
Eventually our primary energy sources will run out. Studies show that oil will run out within approximately 50 years.
Sources of energy like wood, sunlight, wind, waves, running water and the tides are renewable energy sources. This means that they can be replaced.
How does a Toaster Work?
A toaster uses infrared radiation to heat a piece of bread . When you put your bread in and see the coils glow red, the coils are producing infrared radiation. The radiation gently dries and chars the surface of the bread.
The most common way for a toaster to create the infrared radiation is to use nichrome wire wrapped back and forth across a mica sheet, like this.
How Does a Transformer Work?
A transformer is an electrical device that takes electricity of one voltage and changes it into another voltage. You'll see transformers at the top of utility poles and even changing the voltage in a toy train set.
Basically, a transformer changes electricity from high to low voltage using two properties of electricity. In an electric circuit, there is magnetism around it. Second, whenever a magnetic field changes (by moving or by changing strength) a voltage is made. Voltage is the measure of the strength or amount of electrons flowing through a wire.
There's fluoride in your toothpaste and even in your water. But how does it work to keep teeth healthy? Let's find out.
Fluoride is a natural element found in the earth's crust as well as in water and air. It's also considered a nutrient because our bodies need fluoride to grow and develop properly. Decades ago, scientists discovered that kids who naturally had more fluoride in their drinking water had fewer cavities. In the mid-1940s, communities started to put more fluoride in their water supplies to protect people against tooth decay.
|How a Wind Turbine Works|
Wind is a form of solar power. As the earth rotates and the sun heats the atmosphere, the hot air rises above cooler air, creating a current. The wind turns the blades of a turbine, which spins an internal shaft connected to a generator and makes mechanical power or electricity used to power homes and other purposes.
The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS was originally intended for military applications, but in the 1980s, the government made the system available for civilian use. GPS works in any weather conditions, anywhere in the world, 24 hours a day. There are no subscription fees or setup charges to use GPS. See : http://www8.garmin.com/aboutGPS/
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