Return of complicated goods with a defect
If a defect is discovered within half a calendar month after purchase, the buyer can return the product to the store or demand its replacement, if necessary with an additional payment or, conversely, with a deduction of a part of the amount, depending on the prices.
The seller must make a replacement within a week (if quality control is required, the period is extended to 20 days).
After the expiration of the 15-day period, it is possible to return or exchange a product from the List only if it has a significant defect, that is, a defect that cannot be eliminated or which subsequently appears again.
Also, a disadvantage is considered significant if it takes a lot of time and money to eliminate it. In addition, an exchange or refund is possible if the seller, eliminating the defect, did not meet the deadline.
In other cases, a product without a significant defect can only be repaired (under warranty or at its own expense).
Experts advise immediately after the purchase to check the equipment, start using them as early as possible in order to identify all the shortcomings. If they are detected after more than 15 days, it will not be easy to return your money or replace the equipment: you will have to prove that the deficiency is significant.
This should be the rule: as soon as you buy the equipment, check how it works, if there are any external flaws, if everything is in order.
3. Characteristics of measuring instruments
General
characteristics of measuring instruments
are: static characteristics,
reading variations, sensitivity
to the measured value, measuring range,
own consumption of appliances
power, settling time
instrument and its reliability.
For
most types of instruments as
the main characteristic is set
accuracy class, which is
generalized characteristics of funds
measurements that define the limits
allowed basic and additional
errors. Most often, the accuracy class
taken numerically equal to the main
allowable reduced or relative
error, expressed as a percentage.
These values of permissible errors
applied to dials, scales, shields
and cases of measuring instruments.
Errors
means of measurement can be absolute
(v
units of measured quantity
),
relative
(%)
or given
(%).
Absolute
error
,
(1.1)
where
is the value of the measured quantity;
is the true value of the measured quantity.
Absolute
error, taken with the opposite sign,
called an amendment.
Relative
error
expressed
as a percentage of the measured value
quantities
%
(1.2)
Reduced
error
expressed as a percentage of the standard
values
,
most often from the measuring range,
determined by the working part of the scale
measuring
%.
(1.3)
Permissible
error
is the largest error
device.
Main
error
is the allowable error for
normal working conditions established
for the device.
Additional
error
is the error caused by
external environment on the device in case of deviation
conditions for which the device is designed.
For most
Instrumentation allowable error is expressed in
the form of the reduced error in percent
scale range.
According to
GOST 8.401-80 designations of accuracy classes
expressed in numbers: 0.05; 0.1; 0.2; 0.5; 1.0; 1.5;
2.5; 4.0. The accuracy class of the instrument means
that the basic reduced error
instrument in the working range of the scale,
expressed as a percentage, does not exceed
value corresponding to the class
instrument accuracy.
Variation
is the largest difference
when measuring the same value
under constant external conditions. variation
expressed as a percentage of the maximum
instrument scale values
%,
(1.4)
where
–
maximum difference in instrument readings;
– upper and lower limit values
instrument scale.
Cause
the occurrence of variation can serve,
for example, friction in the bearings of the movable
parts of the device.
Important
characteristic of devices is their
sensitivity,
which
expressed in divisions of the scale and calculate
according to the formula
(1.5)
where
–
the amount of movement of the pen or arrow
device;
–
change in the measured quantity that caused
it's a move.
Types of devices
There are two types of cutlery: the main ones, which are used during the meal itself, as well as auxiliary ones, which are created for collective use (for example, to transfer food from the main dish to your plate).
The main group includes:
Snack utensil, which includes a fork and a knife. It is served with cold dishes and snacks, as well as some hot dishes (pancakes, scrambled eggs). The length of the knife is approximately equal to the diameter of the snack plate.
A fish utensil that also consists of a knife and fork. It is used with hot fish dishes. It differs from the diner - the knife slightly resembles a spatula (blunt), and the fork has short teeth.
Cutlery - fork, spoon and knife. With it, you can eat the first and second hot dishes. The length of the knife is approximately equal to the diameter of the dinner plate, and the fork and spoon are slightly shorter.
Dessert tool. It includes a special spoon, fork and knife for sweet dishes. Such a knife is slightly narrower than a diner and the tip is pointed, and the fork has three prongs. These two components of the device are used for cheese, pie, cottage cheese, apple charlotte. A spoon can be used to eat dishes that do not need to be cut.
The fruit cutlery also consists of a knife and fork, which are slightly different from the dessert cutlery - they are smaller and the fork has two prongs. Interestingly, both parts have the same handle.
Chopsticks are a device that came to Slavic cooking from Eastern countries. They are served with Chinese, Japanese, Korean and Vietnamese dishes, while the usual cutlery is not removed.
Spoons - a miniature coffee and a slightly larger teaspoon, as well as a long spoon for cold drinks (for example, tea).
Auxiliary devices include:
Butter knife with a wide, semi-curved blade. It is placed on the right side of the patty plate.
Knife-fork - sickle-shaped with teeth at the end. Serve for cutting cheese.
Knife-saw for cutting lemons, as well as a fork for shifting fruit slices (with two sharp teeth).
Cutlery for fish and seafood: two-pronged fork for herring, fork for sprats (blade-shaped base, 5 prongs), fork and knife for crabs, shrimps, crayfish (with two prongs at the end), fork for oysters, mussels and cold fish cocktails (three prongs, the left one is very powerful for separating the pulp from the body of marine animals).
Salt spoon with a diameter of not more than 1 cm.
A salad spoon, sometimes with three prongs at the end, is slightly larger than a dinner spoon.
Ladles for pouring soups, sweet dishes and milk (they come in different sizes).
Tongs: large (for flour confectionery), small (for sugar, marmalade, chocolate, marshmallows), for cracking nuts (connected in a V-shaped, very strong), for ice (U-shaped bracket with two serrated blades), for asparagus (often served with a special asparagus grill).
Grape scissors for cutting berries from a bunch.
Shoulder blades: caviar (has the shape of a “flat scoop”), rectangular (for meat and vegetable dishes), curly with slots (for fish dishes), curly large (for confectionery), curly small (for pate).
Laboratory equipment
The school also uses laboratory equipment and utensils necessary for conducting experiments and experiments.
Laboratory glassware is very different (Fig. 10).For example, glass. The most commonly used is a test tube in which chemicals are mixed. There is also a glass rod for mixing various substances.
Rice. 10
A watch glass on which solids can be viewed and dishes can be covered during synthesis (Fig. 11).
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There are also funnels for filtering and pouring the substance (Fig. 12).
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Petri dishes (Fig. 13).
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In addition to glassware, there is also porcelain. It includes, first of all, a special cup with a pestle, in which solids are crushed. They also use cups for evaporating substances and measuring instruments (measuring cups, flasks, pipettes, test tubes, cylinders) (Fig. 14).
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Laboratory equipment also includes a special stand to which test tubes, spatulas, holders, thermometers, spirit lamps (Fig. 15), electric stoves, etc. are attached.
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What is included in the list of complex technical goods
The list is compiled and approved by the federal government of the Russian Federation in resolution No. 924 dated October 10, 2011.
It is quite wide and includes equipment for various purposes - both domestic and professional, as well as vehicles. What about technically complex goods?
Super complex technique
This list includes:
- helicopters and light aircraft,
- cars, motorcycles,
- tractors, other special equipment with engines,
- sport courts, snowmobiles, motor boats.
Household appliances
As for household appliances of wide application, falling into the category of technically complex, they include:
- system blocks, laptops,
- monitors, printers and MFPs,
- equipment for broadcasting satellite TV,
- game consoles, TVs,
- photo and video equipment.
Also in the list of technically complex products you will find:
- washing machines and dishwashers,
- refrigerators and electric stoves,
- ovens and coffee machines,
- electric water heaters and air conditioners.
Since the list was compiled, it has already been supplemented more than once, new products have been added to it. Which? For example, in May 2016, the list also included various types of watches - these are mechanical, electronic and hybrid.
What is non-refundable?
Along with Decree No. 924, there is also Decree No. 55 of October 20, 1998 (also repeatedly supplemented), which contains a list of non-food products, as well as goods that cannot be returned or exchanged, provided that they are of good quality.
It includes "technically sophisticated household goods" with a guarantee. This category includes:
- metalworking machines,
- household electrical appliances,
- various radio electronics,
- computers, cameras,
- video cameras,
- phones,
- musical electric instruments,
- children's toys with electronic "stuffing".
What devices in the past helped ships sail
- date
- Category: Transport
Long before the advent of satellites and computers, sailors were helped to surf the oceans by various "cunning" devices. One of the most ancient - the astrolabe - was borrowed from Arab astronomers and simplified for working with it at sea.
With the help of disks and arrows of this device, it was possible to measure the angles between the horizon and the sun or other celestial bodies. And then these angles were translated into the values of the earth's latitude. Gradually, the astrolabe was replaced by simpler and more accurate instruments. These are the transverse rail, quadrant and sextant, invented between the Middle Ages and the Renaissance. Compasses with divisions printed on them and which received an almost modern look back in the 11th century allowed sailors to navigate the ship directly along the intended course.
By the beginning of the 15th century, “blind reckoning” began to be used. To do this, logs were thrown overboard, tied to these ropes - lines. Knots were tied on the ropes after a certain distance. The sundial marked the time of unwinding the line.We divided the length by time and got, of course, very inaccurately, the speed of the vessel.
Latitude reading
In the Middle Ages, sailors determined their position relative to the equator, that is, latitude, by looking at the sun or at the stars. The angle of inclination of the celestial body was found using an astrolabe or a quadrant (figures below). Then they opened their table, which was called the ephemeris, and determined the position of the ship from it.
Measurement of the height of celestial bodies
To measure the height of a celestial body, the navigator had to set a metal rail on this body, looking at the body, drive crossbars of different lengths along the rail until they reached the horizon line. Marks were marked on the rail with the values \u200b\u200bof the heights above the horizon, that is, above sea level.
Determination of longitude
Sailors tried to do this with a sundial and a line - a thick rope with tied knots. The elapsed time was determined by the amount of sand poured out in the clock, and the speed of movement was determined by the length of the line thrown overboard, wound on the ship's view. Multiplying the time of the daily transition by the speed, the distance traveled was obtained. Knowing where the ship started its journey from, in what direction and how much it traveled in a day, one could roughly imagine the movement in the east-west direction, that is, the change in longitude.
The ship pictured below is the Victoria. On it, Magellan and his team made the world's first trip around the world and returned home to Portugal in 1522. Their route is shown as a wavy line on the left on a map issued in 1543.
2. The main characteristics of the electrical measuring instrument
On the
electrical instrument panels
(EIP) indicate the following designations
major
characteristics EIP:
a)
title
instrument:
ammeters, voltmeters, ohmmeters,
wattmeters, counters, etc.
b)
genus
current:
direct current, alternating current devices
current and devices of direct and alternating
current.
v)
system
measuring mechanism of the device:
magnetoelectric, electromagnetic,
electrodynamic, induction,
thermal, etc.
G)
degree
accuracy:
distinguish between eight classes of devices
accuracy - 0.05; 0.1; 0.2; 0.5; 1.0; 1.5; 2.5; 4.0.
The most accurate instruments are
instruments of accuracy class 0.05 (first
accuracy class). Devices firstX
four classes accuracy
used foraccurate
laboratory measurements.
Difference
between the instrument reading and the actual
the value of the measured quantity is called
absolute
instrument error:
|
|
(1) |
,
A
- indications of the working device;
Ad–
actual value
(indication of an exemplary device).
Percentage ratio
absolute error of the device to
the highest value that can
be measured on the scale of this instrument,
called relative
reduced instrument error γ.
|
|
(2) |
,
Aetc
- the largest value of the quantity, which
can be measured with this instrument
(limit
measuring instrument).
the greatest
admissible relative reduced
instrument error is called class
accuracy
this appliance.
Class
instrument accuracy is applied to the EIP scale
as a number with two significant digits,
sometimes circled, sometimes
underlined. The scale of the instrument serves to
reading the value of the measured value.
Ddelenie
scale is called the distance between two
marks closest to each other
scale.
at the cost
division WITH
called the value of the electrical
value per division
scales:
|
|
(3) |
|
|
|
(4) |
,
,
where
dA
– the change
measured value, and dx,
d
—
respectively linear or angular
moving the pointer.
Sensitivity
instrument
(S)
is called the reciprocal of the price
scale divisions:
|
|
(5) |
.
For instance,
there is a device that can measure
voltage from 0 to 250V (250V is the limit
measurements). The scale of this instrument is divided,
for 50 divisions. Then:
WITH=250:50=5V/div,
a S=50:250=
0,2
cases / V.
Scales
there are uniform
and uneven.
On the scale with the help of conventional signs
a detailed technical specification is given
device.
On the
instrument scale indicate:
1)
his
name or letter designation.
For instance,
mA
or
and
etc. By the name of the unit of measurement
value is given the name of the device.
2)
Class
accuracy.
The accuracy class is indicated as a number
one or two significant digits (eg.
– 0.5 or 2.5).
3)
Genus
current
– constant /— / or variable / ~ /,
constant and variable - ~ .
4)
System
measuring mechanism
device. It is indicated on the scale
a special sign representing
a schematic representation
the main node on which it depends
principle of operation of the device (see table
1).
For instance:
-
magnetoelectric
system -
, -
electromagnetic
system -
.
5)Symbol
instrument settings during measurements:
-
horizontal
– →, ┌┐ -
or
at an angle -
6)
Punching
insulation voltage.
The scale shows the voltage
in which the strength was tested
isolation, it is designated as follows:
7)
Degree
protection against external magnetic
fields.
Degree
protection from external magnetic fields
denoted by Roman numerals I,
II,
III,
IV.
A lower number means better protection.
8)
Conditions
operation of the device with appropriate
temperature and relative humidity
are designated
on the scale in letters:
-
A
– normal, works at –10 to +35С° and
ƒ up to 80%, -
B
– Т from –20 to +50С° and ƒ up to 80%, -
V
– Т from –40 to +60 С° ƒup to
98%.
9)
Absolute
instrument error
Absolute
the error given by the measuring
measuring instrument U,
calculated by the formula:
|
|
(6) |
.
10)
On the scale of the device is also applied brand
manufacturer, serial number,
year of manufacture and type of device.
Notation
main systems of measuring mechanisms
electrical measuring instruments are given
in table 1. Table 1.
Classification of measuring instruments
According to the principle of work:
- Showing - those by which you can only read the measured value at a given time; Self-recording (or recording) - equipped with a device for automatically recording data of the measured value for subsequent analysis; Signaling - equipped with a special sound or light alarm that is triggered when the device reaches a predetermined value ;Regulating - having the ability to automatically maintain the value at a given level or change it according to the specified law;Settings - performing certain work according to the measurement result according to the set program. They are used for dosing and weighing bulk and liquid substances, sorting products, etc.
By type of indications: analog (continuous) and digital (discrete).
By type of measured quantity: for measuring temperature, electrical indicators, pressure, humidity, gas density, concentration of solutions, flow and quantity, as well as for determining the composition (analysis) of liquids and gases.
1.4. The main parts of the electrical measuring instrument
TO
the main parts of the electrical
device (IP) include:
-
Frame;
-
clamps;
-
Scale;
-
Index
arrow; -
Measuring
mechanism; -
Screw
corrector (for setting the arrow to
zero mark before measurement,
limiters).
On the
the case of some devices are located:
switch
measurement limits
and arrester.
Arretir
serves to fix the measuring
transport mechanism.
Measuring
mechanisms of any system have a number of common
mechanical parts: coil springs,
axles or half-axes with thrust bearings,
counterweights, corrector.
Spiral
springs
prevent arrow deflection,
what makes it stop
against a certain mark on the scale.
Each measuring mechanism has
your device sedative,
which dampens the vibrations of the arrow after
deviations. Distinguish between air and
magnetic induction dampers.
magnifying devices
Magnifying devices are necessary in order to increase in size even the smallest objects and objects.
The most simply arranged magnifying object are magnifiers (Fig. 1). Magnifiers come in manual and tripod types. In any case, the main part of a magnifying glass is a lens convex on both sides. The hand magnifier has 1 lens inserted into the frame and it has a special handle. The magnifying glass is brought closer to the object until the image is clear enough. Tripod magnifiers have 2 lenses that are attached to a special tripod. And such a magnifier gives a greater magnification. If a hand magnifier gives an increase of up to 10 times, then a tripod - up to 20-25 times.
Rice. one
A more complex magnifying device is a microscope (Fig. 2). At school, as a rule, a light microscope is used, which gives a magnification of 3600 times. The main part of the microscope is the tube - this is a long telescope. There is an eyepiece on one end and lenses on the other. The tube is attached to a tripod. The object table also joins it. On the subject table there are special clamps where the subject glass with the object under consideration is placed. It also has a hole. Under the object stage is a mirror that can capture and direct light. And this light just passes through the hole in the stage. In addition to light, atomic and electronic are currently used.
Rice. 2
Magnifying devices, in addition to those mentioned, also include binoculars, a telescope, and many others.
If during the study we need to determine the length, size, temperature, then measuring instruments are used (Fig. 3).
Rice. 3
Each measuring device has its own scale. It may or may not be signed. The smallest distance between divisions is called the division price (Fig. 4).
Rice. 4
One of the measuring accessories is a ruler. It is used for small measurements, calculations, geometric constructions. Often additional information is placed on the ruler. And those scientists who are engaged in cartography have built-in magnifiers with lenses that move along it.
Another measuring device is a stopwatch (Fig. 5). In the 19th century, it had only one second hand. Hence its name. Now, in addition to seconds, you can measure fractions of a second, and even hours. Most importantly, all stopwatches have an electronic or mechanical device, as well as start, stop and return to 0 buttons.
Rice. 5
Application of measuring machines
Classification of analog measuring instruments
To make accurate measurements, not only hand-held measuring instruments can be used, but also special machines called coordinate measuring equipment. The peculiarity of this equipment lies in the possibility of taking measurements in three coordinates, which ensures maximum accuracy of calculations.
The design of the machines resembles a table on which working heads equipped with sensors are installed. To make a control measurement, the workpiece is placed on the table, and the sensors read the parameters of the part.
Machines can capture data in two ways:
- contact, involving the use of a sensor-probe;
- non-contact, in which reading occurs by directing a light signal to the surface of the part.
Classification edit edit code
According to the type of protection against electric shock, household appliances are divided into five classes - 0; 01; one; 2; 3.Class 0 includes products in which protection is carried out by basic insulation; class 01 - products with basic insulation and equipped with a protective earth clamp; to class 1 - products that have basic insulation and are additionally connected to the grounding core of the cord or have a grounding contact of the plug; to class 2 - products with double insulation (basic and additional) or reinforced insulation; class 3 - products in which protection against electric shock is provided by supplying them from a safe voltage that does not exceed 42 V.
According to the degree of protection against moisture, household appliances are divided into conventional (unprotected), drip-proof, breeze-proof and waterproof appliances.
According to the operating conditions, household electrical appliances and machines are divided into two groups:
- products operating under supervision (vacuum cleaner, coffee grinder, etc.);
- products operating without supervision (fans, refrigerators, etc.).
Electric heaters
Electric heaters are widely used in everyday life. The industry produces more than 50 types of electric heaters for various purposes. Electric heating has a number of advantages compared to other types of heating: high efficiency. (up to 95%), no harmful emissions, the ability to automate power and temperature control. The transformation of an electrical network into a thermal one in household appliances is carried out by high-resistance conductors, infrared, induction and high-frequency heating.
The range of electric heaters according to their intended purpose is classified into the following subgroups:
- appliances for cooking and heating food,
- water heating,
- ironing,
- space heating,
- human body heating
- electric tool.
Appliances for cooking and heating food
Appliances for cooking general purpose - electric stoves and portable electric stoves. The working part of these devices are burners (cast iron, with heating elements, etc.). Tiles are produced with one and two burners with a diameter of 145 and 180 mm, with a power of 800 to 1200 W (express burners & m - 1500 and 2000 W). Tiles have a three-stage heating control, plates - three or five stages.
Devices for heating and maintaining the temperature of food - food warmers, baby food warmers, thermostats.
Bain-marie - metal or ceramic coasters with a built-in electric heater that heats the work surface up to 100 ° C.
Baby food warmers are containers with thermal insulation or double walls, between which there is a heating element of low power.
Thermostats are thermally insulated cabinets in which a temperature of about 70 ° C is maintained using a thermostat.
Additional Information
invention of the microscope
This discovery is primarily associated with the development of optics. In 1595, Zaharius Janson was the first to mount something similar to a microscope (Fig. 16). But the increase it gave from 3 to 10 times. The author constantly improved his invention.
Rice. sixteen
In 1609, Galileo Galilei changed his telescope a little and learned how to change the distance between the eyepiece and the objective. And for the first time he began to use it as a kind of microscope.
In 1625, the term "microscope" was first proposed. Faber introduced it. And in 1665, Anthony van Leeuwenhoek examined the structure of a plant cell. And he described the structure of his more advanced microscope (Fig. 17).
Rice. 17
In 1681, Robert Hooke discovered animal microorganisms. The magnification of his microscope was 270 times. Here is what he described:
Rice. eighteen
scales
The first mention of scales dates back to the 2nd millennium BC. It is believed that they appeared in ancient Babylon and Egypt. It was an equal-arm scale with two suspended bowls (Fig. 19).
Rice. nineteen
And later, unequal scales with a mobile weight appeared (Fig. 20).
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In the 12th century, scales with an error of 0.1% were created. They were used to detect counterfeit coins and stones.
Galileo Galilei created a hydrostatic balance to determine density.
Since the advent of scales, people have always been interested in the question of their accuracy. And therefore, in Russia in 996, Prince Vladimir leads a single measure of weights.
In the 12th century, in the decree of Prince Vsevolod, it was said about the annual check of the scales.
In 1723, in the decree of Peter the Great, information about scales also appears. He says:
Rice. 21
In 1841, a building was built on the territory of the Peter and Paul Fortress - a kind of depot for weights and measures. All merchants brought their scales to be checked there.
In 1918, a decree was adopted on the introduction of the international metric decimal system of measures and weights. The kilogram was taken as the basis of the unit of weight.
List of recommended literature
1. Melchakov L.F., Skatnik M.N. Natural history: textbook. for 3, 5 cells. avg. school – 8th ed. – M.: Enlightenment, 1992. – 240 p.: ill.
2. Bakhchieva O.A., Klyuchnikova N.M., Pyatunina S.K. and others. Natural history 5. - M .: Educational literature.
3. Eskov K.Yu. et al. Natural History 5 / Ed. Vakhrusheva A.A.– M.: Balass.
Recommended links to Internet resources
1. Microscopy.ru (Source).
2. Physics.ru (Source).
3. Evolution (Source).
Recommended homework
1. What groups are the equipment for scientific research divided into?
2. What magnifying devices exist?
3. What are the measuring instruments?
4. *Prepare a short report on the history of the invention and improvement of any research equipment of your choice.
Key features
- Maximum measurement limit; Permissible error limit.
Rental of measuring instruments is a service for performing a specific task when the purchase is not feasible. Our company offers a wide range of construction tools for hire at the lowest prices.
Measurement is the process of determining a physical quantity using technical means.
A measure is a means of measuring a physical quantity of a given size.
A measuring device is a means of measurement in which a signal is generated that is available for perception by an observer.
Measures and devices are divided into exemplary and working. Exemplary measures and devices serve to verify working measuring instruments on them. Working measures and devices serve for practical measurements.
Hand tool
In addition to the universal ruler and tape measure, the locksmith has to use the following devices:
- calipers;
- height weight;
- micrometer.
Calipers. This hand tool consists of a graduated shaft and a moving frame. The caliper is also equipped with upper and lower jaws. The upper jaws allow you to measure the internal parts of the workpieces, and the lower jaws allow you to measure the external parts.
Diagram of a caliper
Stangenheightmass. This device differs from a caliper in the presence of a support. Height gauge allows you to mark the height and depth of holes, as well as the location of other elements, on parts.
sternheightmass
Micrometer. The design of this device consists of a tube with a scale, a sleeve and a tip. A micrometer is used if it is required to calculate the value with an accuracy of 0.01 mm. The depth of holes in parts is measured with a micrometer depth gauge - a type of micrometer.
Tube micrometer device
