Physics Grade 8
"Theory of jet propulsion" - Jet engines. Pp. P=M·V The momentum of the fuel-Pt is equal to the momentum of the rocket Рр, but is directed in the opposite direction. O=mpvp+mtvt mpvp=mtvt Vp=mt vt. Jet propulsion in nature. Aircrafts. Examples of jet propulsion. Jet propulsion. Squid. Konstantin Eduardovich Tsiolkovsky. Completed by: Pupil of 8 "A" class of the Gymnasium No. 363 Zhurkin Alexey. Tsiolkovsky formula. Theory of jet propulsion. Work goals. Pt. mp. Rocket weapon Katyusha (BM-13).
"Electrical instruments" - VOLTMETER - a device for measuring voltage in a section of an electrical circuit. Classification. 3) Ohmmeters - for measuring electrical resistance. 6) Multimeters (otherwise testers, avometers) - combined devices. Voltmeter: the needle turns in the magnetic field of the magnet. It has a sensitive element called a galvanometer. 4) Electric meters - to measure the consumed electricity.
"Lomonosov's Activities" - In the next five years (1750-1755), Lomonosov's activities are also deployed on a broad front. Lomonosov's parents. M. V. Lomonosov began to learn to read and write at the age of 11-12. Slavic-Greek-Latin Academy. Lomonosov arrived in Moscow in early January 1731. The work was done by a student of the 8th "b" class Guryanova Anastasia. The school was located in the building of the Sukharev tower. New period in life. Physics. Works of Lomonosov in the field of language. Training took place all year round. Lomonosov is 300 years old. No less valuable were Lomonosov's research in the field of physics. Reviews about Lomonosov. Long haul……..
"The structure of the electron shells of atoms" - Integration of physics with chemistry Grade 8. The maximum number of electrons in an energy level. Learn to write electronic formulas of atoms. . Generalization of the studied material. °. The nucleus of a carbon atom contains 12 particles. The chlorine atom has accepted one electron. Integrated lesson.
“Thermal phenomena grade 8” - Is mom right when she calls her child “You are my sun”? Day old chicks should not be kept under the new energy-saving lamps? MBOU "Verkh-Chebulinskaya secondary school". The moon shines, but does not warm? Have you thought about the question: Why is it comfortable to live in a modern house? The purpose of the project: Do you know how a person takes into account thermal phenomena in everyday life? It turns out that thermal phenomena accompany us everywhere! 2. It is not clear why...?
"Flat mirror" - The table seems to the audience to be standing on four legs. On which side of your mirror double is the heart? How is the image of a point in a plane mirror obtained? Solar concentrators. Flat mirrors are used in some circus tricks. The units are used to produce high temperature steam. The use of mirrors in technology. Physics lesson in grade 8 on the topic "Flat mirror".
"Physics Grade 8"
Homemade solar concentrator oven
To begin with, it is worth identifying the place of concentration, for this, put on sunglasses. Take a wooden board and tight mittens. Point the reflector towards the sun and focus the captured rays on the board, then adjust the distance until you get the most efficient, concentrated beam of energy, do this until you get its smallest size. The mittens you wear will protect your skin from sunburn if you accidentally put your hands in the focus area of the rays. After you determine the point of concentration, you will only have to fix the structure and finish its installation in the optimal place. As they say in inventor circles, "The only thing left to do is get a patent." Use the results of your work, getting an inexhaustible and free source of energy.
Stirling engine can be assembled using improvised, common materials
There are many options for manufacturing concentrators based on solar radiation. In the same way, you yourself, using improvised, common materials, can assemble a Stirling engine (it is really possible, although, at first glance, it seems unattainable), and you can use the capabilities of this engine for a variety of purposes for a long time. All restrictions depend only on your patience and imagination.
The inspiration for the construction of this unit was the MythBusters program on the Discovery Channel. In this program, the "destroyers" tested the myth of how Archimedes burned the Roman fleet with the help of mirrors. This myth has been busted twice. But nevertheless, it is possible to build a simple focusing mirror that can set fire to a board or cook dinner.
This will require very little.
1. Self-adhesive mirror film (can be bought at wallpaper stores). Window film will not work.
2. Chipboard sheet and the same hardboard.
3. Thin hose and sealant.
A ring is cut out of chipboard. Later I needed two rings. Otherwise, the beam will focus too far. The ring is cut with a jigsaw.
Under the size of the ring, a circle is cut out of hardboard.
The ring is glued to the hardboard
It is important to coat everything well with sealant. The design must be airtight and not let air through.
We make a hole on the side and insert the hose.
And finally, we stretch the mirror film on top.
Then the air is pumped out of the housing and a spherical mirror is obtained. The hose is bent and clamped with a clothespin.
For this unit, it is desirable to make a stand.
Fuck this thing be healthy.
It turned out to achieve good focus. The only bad thing is that this mirror cannot be directed to an arbitrary point. Only in the sun.
Calculate mirror profiles
The main mirror is a parabola and is described by the function
The small mirror according to the Gregory scheme is an ellipse and is described by the function
where e is the eccentricity of the generating ellipse of the small mirror (e = 0.3022
The calculated mirror profiles have the form:
irradiator antenna mirror focal
Calculation of the irradiator
We will use a dielectric rod as an irradiator. The radiation pattern of a dielectric rod can be calculated using the following approximate relationships:
where is the length of the rod in meters, is the deceleration coefficient. selected according to the graphs in Fig. 5.2 Part 1, depending on the cross section of the rod and the long wave, is the diameter of the rod.
k is the wave number and is calculated according to the formula: k = 2r/l = 209.4395 m-1
dielectric permittivity is selected together with such a parameter as: wavelength, according to the following dependencies:
To ensure the required width of the DN of the dielectric rod, that is, by choosing the necessary parameters of the antenna, in the ANT-4 program, changing the degree of the approximating polynomial, we achieve the necessary indicators of the antenna efficiency, choosing the required total, we choose the length of the rod that satisfies us, changing the parameter k1, the deceleration coefficient, we obtain the required width of the DN, and then we select the rod material according to these graphs.
— maximum rod diameter
- the diameter of the rod selected for this antenna, the dielectric constant and the width of the pattern depend on this parameter.
- rod radius
- the length of the rod on this parameter, the width of the DN and the choice of the dielectric also depend.
- the deceleration coefficient is selected in accordance with the graphs above.
- attenuation factor
- efficiency factor
To obtain the maximum value of the directivity factor of a reflector antenna, the main lobe of the RP of the dielectric irradiator within the irradiation sector of the small mirror must be symmetrical. To do this, within the irradiation angle, the RP in the E and H planes must be symmetrical:
is the coefficient of energy interception by the small mirror.
Phase center: for a cylindrical rod, it is approximately taken in the middle of the rod.
To excite the waveguide, we will use an electric vibrator, which we will bring to the waveguide using a coaxial line with a TEM wave. The outer conductor is connected to the waveguide, and the inner conductor is placed directly in the waveguide. The structure of the field excited in the waveguide by this vibrator will have the same distribution as in the line, therefore, waves will be excited, in which antinodes are in the center, these are type waves, etc. waves with the first odd index, and waves of the type will not be excited, for a single wave mode, it is necessary to appropriately select the dimensions of the waveguide, at which waves of higher types will fade, to work with a wave, the necessary condition: . In order for our antenna to work on a given type of wave and higher types of waves do not fall into it, the distance from the vibrator to the dielectric rod must be greater (wavelength in the waveguide). Because vibrator radiates a wave in both directions, then to improve the matching, we will introduce the vibrator into the waveguide at a distance , with this arrangement, the phase incursion of the reflected wave from the back wall will be equal to p and it will add up with the wave propagating towards the rod.
To obtain horizontal polarization in a rectangular waveguide, there are two ways, either to introduce a vibrator into the waveguide from the side of a small wall, or to excite a wave in a rectangular waveguide, and then smoothly rotate the waveguide by 90 degrees. Let's use the second method, because this method is simple to perform and does not require the purchase of a waveguide with an additional input from the side of the small wall. The requirement for the turning section, its length, must be greater than the wavelength in the waveguide, because waves of higher orders are excited there and they must have time to decay.
Waveguide calculation:
The dielectric rod is powered by a rectangular waveguide in which the H wave propagates.10. In order to avoid excitation of waves of higher types in the waveguide, it is necessary to choose its dimensions in such a way that .
Rectangular waveguide dimensions:
EIA-62
The transition from the waveguide to the rod is carried out using a cone-shaped washer, which will go from a diameter of 15.8mm to a rod diameter of 8mm
The field structure of the selected wave field in the given waveguide:
See drawings of the waveguide and rod at the end of the work.
How to build a solar concentrator with your own hands from improvised materials, a free guide from GoSol video
Details Published: 10/12/2015 08:32
Startup company GoSol intends to make solar energy available to everyone on a global scale. To do this, she created an initiative to develop and disseminate instructions for assembling solar concentrators from local materials that could become efficient sources of heat for cooking, washing, heating water and heating.
“The mission of GoSol.org is to eradicate energy poverty and minimize the effects of global warming by spreading our DIY technology (DIY from English. Do It Yourself - Russian “do it yourself”) and breaking down any barriers to free access to solar energy. With your help, we want to engage communities, entrepreneurs and craftsmen to use the world's most powerful source of energy. All the materials and tools needed to implement these technologies have already been produced and are in abundance in all corners of the world, ”says the GoSol website.
GoSol enthusiasts have launched a campaign with which they intend to raise $68,000 to make their goal come true. So far, the initiative has raised about $27,000 and most recently, GoSol released its first instruction manual for building a solar concentrator.
This free step-by-step guide contains all the information you need to build your own 0.5 kW solar concentrator. The reflective surface of the device will have an area of about 1 square meter, and the cost of its production will cost from $79 to $145, depending on the region of residence.
Sol1, as GoSol's solar plant is named, will take up approximately 1.5 cubic meters of space. Work on its manufacture will take about a week. The materials for its construction will be iron corners, plastic boxes, steel bars, and the main working element - a reflective hemisphere - is proposed to be made from pieces of an ordinary bathroom mirror.
The solar concentrator can be used for baking, frying, heating water or food preservation through dehydration. The device can also serve as a demonstration of the efficient operation of solar energy and will help many entrepreneurs in developing countries to start their own business. In addition to helping to reduce harmful emissions into the atmosphere, GoSol solar concentrators will help reduce deforestation by replacing burned wood with clean solar energy.
The GoSol instruction can be used not only to create and implement, but also to sell solar concentrators, which will help to significantly lower the threshold for access to solar energy, which is mainly generated today through photovoltaic solar panels. Their cost remains at an extremely high level in regions where it is often simply not possible to obtain energy in other ways.
Solution
1.
Definition of the Fresnel number
Since the diameters of the resonator mirrors are the same, for
calculation of the Fresnel number, you must use the formula (10) of work:
, (26)
where a is the radius of the mirrors. Substituting
the value of the quantities included in formula (26), we obtain
(27)
2.
Determination of the loss factor
According to the condition, the total losses are mainly determined by
mirror transmission losses, losses due to inaccurate resonator alignment
and diffraction loss. Each type of loss has its own coefficient
losses. Therefore, the total loss factor will be the sum of these
coefficients:
(28)
For
calculation of the first term in (28), we can use formula (4),
the second - by formula (5), and the third - by formula (6) of the work. Then
(29)
Substituting
in (29) the values of the corresponding quantities, we obtain (a=0.4
cm)
(30)
3. Determination of the quality factor of the resonator
It is known that the quality factor of the resonator is determined by the value
loss of radiation propagating inside it. Since it is required
determine the quality factor for the fundamental transverse mode, then can be used to
This is the total loss factor (30) calculated above. In this case, according to
work , the quality factor can be written by the formula (26)
. (31)
Substituting into (31) the values
corresponding values, we get
(32)
Photon lifetime in the fundamental transverse cavity mode
it is easy to determine from the formula (25) of work :
, (33)
where -
the center frequency of this mode is its wavelength,
Withis the speed of light in vacuum. From (33) it follows
. (34)
Resonance curve width,
describing the shape of the spectral line of the resonator at the frequency of the main transverse
mode, can be calculated from formula (37) of work :
(35)
4.
Determination of the degree of stability of the resonator
It is known that in the geometric approximation the condition
resonator stability has the form (see formula (53) in )
, (36)
where are
generalized resonator parameters. Calculating these parameters gives
, (37)
The work satisfies
condition (36), therefore, the resonator is stable.
5. Determination of the frequency spectrum of laser radiation
The laser resonator is essential and
even fundamentally affects the properties of the output radiation. The fact,
that during its propagation inside the resonator between its mirrors, the radiation
is formed into a certain state of the electromagnetic field, which are called
resonator oscillation typesor mods.
Each mode is characterized by a certain spatial structure of this field
(i.e., a certain distribution of amplitude and phase) transverse to the axis
resonator direction, in particular on the surface of the resonator mirrors. Besides
In addition, each mode is characterized by a certain phase shift per double pass
resonator.
How to Build a High Efficiency Solar Water Heater from a Parabolic Antenna
Itself can be made on the basis of the front hub of a VAZ car.
For those who are interested, the photo was taken from here: Rotary mechanism Step 3 Creating a heat exchanger-collector To make a heat exchanger, you need a copper tube coiled into a ring and placed at the focus of our concentrator. But first we need to know the size of the focal point of the dish. To do this, you need to remove the LNB converter from the dish, leaving the converter mounts. Now you need to turn the plate in the sun, after fixing a piece of the board at the place where the converter is attached. Hold the board in this position for a while until smoke appears. This will take approximately 10-15 seconds. After that, unscrew the antenna from the sun, remove the board from the mount. All manipulations with the antenna, its turns, are carried out so that you do not accidentally stick your hand into the focus of the mirror - this is dangerous, you can get burned badly. Let it cool down. Measure the size of the burned piece of wood - this will be the size of your heat exchanger. The size of the focus point will determine how much copper tubing you will need. The author needed 6 meters of pipe with a spot size of 13 cm. I think that it is possible, instead of a rolled tube, to put a radiator from a car stove, there are quite small radiators. The radiator should be blackened for better heat absorption. If you decide to use a tube, you should try to bend it without kinks or kinks. Usually, for this, the tube is filled with sand, closed on both sides and bent on some mandrel of a suitable diameter. The author poured water into the tube and put it in the freezer, open ends up so that the water does not leak out. The ice in the tube will create pressure from the inside, which will avoid kinks. This will allow the pipe to be bent with a smaller bend radius. It must be folded along a cone - each turn should be not much larger in diameter than the previous one. You can solder the turns of the collector together for a more rigid design. And don't forget to drain the water after you're done with the collector so you don't get burned by the steam or hot water after putting it back in place. Step 4. Putting it all together and trying it out. container, or plastic container, complete manifold. All that remains to be done is to install the collector in place and test it in operation. You can go further and improve the design by making something like a pan with insulation and putting it on the back of the collector. The tracking mechanism must track movement from east to west, i.e. turn during the day to follow the sun. And the seasonal positions of the star (up / down) can be adjusted manually once a week. You can, of course, add a tracking mechanism vertically as well - then you will get almost automatic operation of the installation. If you are planning to use the water for pool heating or as hot water in the plumbing, you will need a pump that will pump the water through the manifold. If you heat a container of water, you need to take measures to avoid boiling water and explosion of the tank.This can be done using an electronic thermostat, which, if the set temperature is reached, will divert the mirror from the sun using the tracking mechanism. I will add on my own that using a collector in winter, measures must be taken so that the water does not freeze at night and in inclement weather. To do this, it is better to make a closed cycle - on the one hand, a collector, and on the other, a heat exchanger. Fill the system with oil - it can be heated to a higher temperature, up to 300 degrees, and it will not freeze in the cold.
Ripasso solar concentrator - the most efficient way to convert solar energy
- Details
-
Published: 05/18/2015 13:23
When it comes to solar power generation, process efficiency is key. South Africa's new solar project in the Kalahari desert is arguably the most efficient system in the world today. The Swedish energy company Ripasso, taking advantage of the bright African sun, intends to test its solar concentrator, which combines modern military technology and the ideas of a priestly engineer from Scotland in the 19th century. As a result of a technical "symbiosis", the system is able to convert 34% of solar energy into electricity, sent directly to the grid. This efficiency is almost twice the efficiency of traditional solar panels.
At the moment, there is only one working example of a Ripasso solar concentrator with similar characteristics, but its creators hope that the system will become one of the most sought-after renewable sources on the planet. The device is equipped with a mirror reflector with a total area of 100 m2, a giant disk rotates following the movement of the sun and constantly adjusts to extract the maximum solar energy.
Independent tests of the project have shown that one such reflector can generate 75-85 megawatt hours of "green" energy per year - enough to provide electricity for ten average households for a year. For comparison: in the production of the same amount of electricity from coal burned at thermal power plants, 81 tons of CO2 will be released into the atmosphere.
Related article: Solar panels to become more efficient, superhydrophobic glass invented
The Ripasso solar power plant is powered by mirrors that focus, like giant lenses, sunlight into a small point. Heat energy powers the Stirling Engine, patented by Scottish engineer Robert Stirling in 1816. At that time, it became the first alternative to the steam engine. The operation of the device is based on the alternating heating and cooling of gas in a closed space, which drives a piston that rotates a flywheel. Due to the lack of suitable materials in those years, the engine was not mass-produced. The commercial release of the invention started only in 1988, when the Swedish Ministry of Defense began to produce them for submarines. Project manager Gunnar Larsson spent 20 years working for the Swedish defense industry before finding a renewable energy application for the engine.
The system has been tested in harsh desert conditions for more than 4 years, and before that there were years of successful tests in the Navy. The creators of the solar collector note that in order to achieve commercial success, in addition to efficiency, the low cost of the technology will become a determining factor - it must compete on equal terms with photovoltaic systems, the prices of which are falling every year. The disadvantages of the new concentrator include the inexpediency of its use in areas where there is no constant solar radiation.
Source theguardian.com
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Assembly and connection diagram
Do-it-yourself solar power plant is assembled like this:
- Find the output terminals of the charge controller, connect the battery to it. After that, connect the conductors that extend from each panel to the input terminal of the charge control device. If the panels come with a cable, this step is not needed.
- It is required to connect the conductors according to the scheme "+" to "+", as well as "-" to "-". After that, the terminals located at the input of the inverter are supplied with power from the battery.
- By turning on the charge controller and the inverter, you will see that the electricity that the panel starts to generate will charge the battery.
Scheme of connecting solar panels and household load
