Simple-Science - Simple experiments with a microwave (digest # 16)
This digest of " Simple experiments " is not quite similar to all the previous ones. And the point is not in the microwave. Today we tried to give an explanation to each experiment: " Why is this happening ." If anyone has any comments or comments, we will be grateful for them.
Today in the "microwave":
- incandescent and fluorescent;
- Laundry soap and toilet;
- packs with chips;
- laser discs;
- metal pins;
- balloon.
Attention:
Experiments can be dangerous not only for health, but also for the microwave.See below 6 videos.
Microwave light bulbs
Why do lamps glow in the microwave
Electromagnetic waves penetrate the glass and, creating eddy currents on the surface of the tungsten filament, heat it. The thread is heated and shines. Due to microwaves, an electric arc forms in a light bulb with a dangling filament, which allows you to see the glow.
In a fluorescent lamp, the glow is visible due to the conversion of ultraviolet radiation into visible light by means of a phosphor (a special substance that covers the inner walls of the bulb). more details
Soap in the microwave
Why does soap swell in the microwave
The main component of solid soap are sodium salts of higher fatty acids. Also in its composition there is water, perfumes, and other additives (optional).
Microwaves primarily heat the water in the soap, and it boils, turns into steam. The gas, expanding, seeks to be released and presses on a solid foundation around itself. Bubbles form that foam the mass. Most of them “break through”, and steam is released, leaving behind a finely porous structure. This is how soap foams in an anhydrous environment. more details
Packs of chips in the microwave
Why does the package spark in the microwave
Polypropylene film coated with a thin layer of aluminum and paint is standard for bags.
Waves do not penetrate into the package, as they are reflected from the metal layer. In this case, induced currents are formed on the surface. In some places there is an electric arc that creates the effect of lightning - a sparkling surface. Under the influence of current, the metal heats up. Following it, due to the high temperature, the inner layer of polypropylene melts. When melted, it “shrinks” like an ordinary plastic bottle, if you pour cool boiling water into it. Polypropylene begins to bubble and turns the sealed bag into a bag-sieve (simply leaky). After that, the spark almost stops! Why would you?
The fact is that now microwaves can penetrate and absorb through the holes in the package - chips. Therefore, the thermal and electrical load on the package is reduced. more details
Microwave laser discs
Why do sparks spark in the microwave
The surface of the disk consists of several layers: protective, reflective and active. The reflective layer is a metal, usually aluminum. There are several types and generations of optical discs. In this experiment, DVD and BD were used.
Microwaves pass through the protective layer and are reflected in the metal. And, as is the case with any metal conductor, induced electricity arises in it. Sparks are an electric discharge. The metal heats up and melts. The plastic of which the base consists also begins to melt.
The difference in the degree of reflow, the structure of the pattern on both disks and the strength of the “sparking” is explained by the unequal thickness and composition of the materials used to make their coatings. more details
Microwave metal pins
Why metal pins sparkle and heat up to glow in the microwave
Our pins are metal, and therefore are conductors. Waves emitted by the furnace are not absorbed by bodies, as is the case with products, and are not quenched. Under the influence of an electromagnetic field in the conductor, induced electricity and eddy currents occur. The appearance of sparks is nothing more than an electrical discharge (arc) between two conductors that are close to each other.
The bodies in which such currents occur are heated. In this case, very much. This is explained by the Joule – Lenz law for thin conductors, from which it follows that the amount of heat released in a period of time is proportional to the product of the squared current and resistance. And this is a lot. more details
Microwave balloon
Why does a latex balloon burst in the microwave
Balloons are made, as a rule, of latex. Latex is a natural or artificial aqueous dispersion of colloidal rubber particles stabilized by emulsifiers.
The key word here is "water." That is, the material for balloons contains water molecules. Latex transmits electromagnetic waves. In this case, dipole water molecules under the influence of microwaves begin to rotate millions of times per second, creating friction. The result of this is an increase in the temperature of the substance. Latex begins to melt, the walls of the ball become thinner, and at some point it bursts under the pressure of air. In the place where the thickness is critically minimal for the pressure inside the ball. more
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