How do freezers produce ice? How do food items get cold inside refrigerators? And how do air-conditioning units release cool air? All these appliances use the same process to function – refrigeration. But to know what refrigeration is, we need to understand the science of thermodynamics in the simplest way possible.
Thermodynamics has something to do with heat? Yes, it is about heat, which is ironically the opposite of coldness, which is our topic. To make it simple, let us define the word "cold" as an adjective characterized by the low degree of heat. Also, let us define refrigeration as the process of removing heat from an object to make it cold. With these twin definitions, we assume that freezers, refrigerators and air-conditioning units are machines that take away heat from an object or a surface. In other words, these machines suck heat out of an enclosed space.
Taking away heat from an object is possible through the system of evaporation. Have you ever observed that it becomes cooler after it had rained. This is because the rain, the perfect result of evaporation, takes away the heat of the soil. Have you ever felt fresher after taking a bath. This is because the water on your body takes away some of the heat from your skin.
In the Philippines, teachers focus more on the definition of electricity and the people who discovered it than on how it is produced in the first place. We know that Benjamin Fraklin, the greatest American statesman and inventor, was the one who discovered the nature of electricity through his experiments with lightning in 1740s. Thomas Edison applied electricity to light a bulb in 1879 while Nikola Tesla developed a system of generating and transmitting alternating current (AC) electricity in the 19th Century. James Watt, on the other hand, invented the steam engine, which remains the basic structure of most engines and power generators to this day.
Alexander Graham Bell was credited for having invented the telephone on March 10, 1876. It was a magnificent invention, that helped us in so many ways. It is only proper that we give proper recognition to this device by trying to understand how it functions. But we would not go to the extent of explaining acoustics or the science of sound to make our point.
First let us define telephone as a device capable of replicating voice and transmitting it from one point to another in the fastest means possible. Imagine, we can now hear the replicated voice of our relatives on the other side of the planet in a matter of seconds through telephone wires. Yes, the voice we hear on the phone is a product of replication by devices.
Let us try to define some terms in simple language. Human voice is a sound, which is produced by the movement or vibration of our lips, tounge and mouth. Sound wave travels through the air, water or solid objects. It is important to realize that sound can be converted into electrical energy, which we will elaborate later. Telephone is a device that can transform sound into electrical energy and transmit it through copper wires to another point.
Rather than asking students who invented the airplane, it is important that Filipino educators begin explaining to their students what makes an airplane fly? We all know that Orville and Wilbur Wright developed a flying machine that first lifted from the grounds of Kitty Hawk, North Carolina and stayed on the air for 12 seconds on December 17, 1903. But it is time for both teachers and students to know how and why that machine flew in the first place.
Instead of using aerodynamics terms to explain the theory of flight, it will be useful to explain it in the simplest way possible. An airplane is able to fly because it applies a force created by a propeller, which is strong enough to make it move forward and uses wings or airfoil to deflect air pressures in such a way that the wind pushes back from underneath the wings to lift the whole airplane.