Vacuum Cleaners: Explained.

 

Vacuum Cleaners:

            Materials flow from one location to another when the pressure difference is created between two locations. A vacuum cleaner is based on that principle.

The suction will be created in front of the centrifugal fan and negative pressure will create behind the centrifugal fan.

Working:

            Now let’s have a look at the working of a vacuum cleaner with parts. Firstly, we have a vacuum cleaner chamber. On the front of the vacuum cleaner chamber, there is a filter for filtering the dust particles and giving clean air to the front area. There is a motor and a centrifugal fan with a pipe attached to the cleaning apparatus. Now, we see the working of a vacuum cleaner. When we apply voltage to the cleaner, the fan will start rotating, creating a pressure difference. Then, this pressure difference will suck the air from this pipe and this pipe will suck the air with the dust particles and this air with dust particles will reach the filter. There, it will be filtered and clean air will be aborted from the filter. This clean air will reach the atmosphere, so this difference of pressure will suck the air from the outside to inside in the vacuum cleaner suction pressure will be created in the front of the centrifugal fan and negative pressure we create in the behind of the centrifugal fan.

 

This was the working of a simple vacuum cleaner.

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Microwave ovens: Explained.

 

Microwave ovens could be one of the greatest inventions of the 20th century. But how exactly do they work?

Let's explore the science behind it.

Microwaves:

            Microwaves are electromagnetic waves that fall in between radio waves and infrared waves on the electromagnetic spectrum.

Microwave Ovens:

            Microwave ovens use microwaves to heat the food while radio waves can be tens of kilometers long. Microwaves used in cooking are just about 12 centimeters from crest to crest.

With the frequency of 2.45 gigahertz, waves at these frequencies are absorbed by food molecules especially, the molecules of water. These water molecules have a positive and negative end same as a bar magnet with a North and South Pole. As the microwave changes its polarity, the polar molecules rotate at the same frequency millions of times a second. To line up with the changing field, all this agitation on the molecular level creates friction which heats up the food. But since, microwaves don't interact with plastics, glass, or ceramics, only the food is heated

So how does a microwave oven turn electricity into heat?

            Inside the strong metal box, microwaves are created using a device called a magnetron.

A transformer steps up the standard household electricity from the wall socket to around 4000 volts. This increased voltage heats up the cathode or the filament which is at the center of the device. A ring-shaped anode surrounds the filament and electrons are emitted as the filament heats up and rushed towards the anode or the positive terminal. The anode has slots cut into it called resonant cavities.

            Two ring magnets are placed above and below the anode, which generates a magnetic field that is parallel to the cathode. Normally when the filament is heated, the electrons which are negatively charged particles would rush out in a straight line towards an anode, which has a positive potential. However, due to the magnetic field, the electrons bend back towards the filament and follow a curved path. These electrons spiral as they leave the filament-forming an interesting pinwheel pattern.

As the charges on the cavities oscillate, the tip of the pinwheel spins which in turn creates microwaves in the resonant cavities.

            The microwaves are then transmitted into the compartment through a channel called a waveguide. These waves bounce back and forth off the reflexive mirror eventually penetrating the food in turn heating it up.

 

This was the working principle of a microwave oven.

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Refrigerators: Explained.

 

Introduction:

            Before refrigeration, keeping food fresh was a pretty tough job. In those days, people used to salt their food or bury it in the snow to keep it fresh. But now, the refrigerator has changed the way we conduct our daily lives, making it easier to preserve food.

Working:

            Have you ever wondered that how a refrigerator keeps your food fresh and provides you with a refreshingly chilled beverage on a hot day? Well, let's find out.

            Refrigeration is actually quite simple to understand the principles behind it. Just remember that when the liquid evaporates, it absorbs heat and when it condenses, it releases heat.

A simple example is that when your hand is wet, it feels cold. This is the process of the water evaporating and cooling your hand on a very humid hot day.

Components:

            A refrigerator uses five major components:

·         An expansion device

·         Evaporator coils

·         A compressor

·         Condenser coils

·         A refrigerant

            The refrigerant is a liquid that enters in the expansion device. As it passes through, the sudden drop in pressure makes it expand cool, and turn into a gas. As the refrigerant flows around the evaporator coil, it absorbs and removes heat from the food inside. The compressor squeezes the refrigerant, raising its temperature and pressure. It's now a hot high-pressure gas. The refrigerant then flows through condenser coils on the back of the fridge, radiating its heat to the atmosphere and cooling back into a liquid. As it does so, the refrigerant then re-enters the expansion device and the cycle repeats itself. So basically, heat is constantly picked up from the inside of the refrigerator and taken outside of it.

 

 

Stay tuned.

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