# Tip 1: How to calculate the amount of building materials

any construction - is the high cost, and the more expensive and high-quality material, the more important to calculate the costs in advance.Buying too much will lead to waste and excess reserves, and if as a result of something is not enough, would have to go to the store to spend money on the road and your precious time.To avoid this, you need to accurately calculate the amount of building materials.
you need
• - Roulette;
• - pencil;
• - level or plumb line;
• - calculator and sheet of paper.
Guide
1
If you need to calculate number cement and sand for plastering walls, take the beacons and set them on the wall on the vertical level, making sure that the thickness of the future plaster was not less than 15 cm.
2
Take a tape measure and measure the height of the wall and its width, multiply the value of each other - you get plastered surface area.If the wall is not flat and the thickness of the plaster is not the same, make measurements of the thickness in different places, and then
add each other to get the data and divide them into number of measurements.The resulting number is the average thickness of the plaster.Multiply the area of ​​the wall to an average thickness of plaster layer.You've got the volume of cement-sand mixture.
3
The solution includes sand and cement in certain proportions, quite mistakenly confuse them without checking.Calculate the absorbency cement sand.To do this, take one bucket of sand and add 1/4 of the cement.Pe6remeshayte solution and fold back into the bucket.If you got a bucket without a trace, then cement is completely melted and filled in all the gaps between the crystals of sand.Otherwise, you have gone too far with cement.
4
calculate the exact consistency of the solution.Usually it turns out 1: 4.Divide the amount obtained from the previous estimates of 4 plus 1. You've got a number that corresponds to the amount of cement, the rest of the sand.
5
To calculate the number of putty on a flat wall, proceed as follows: wall area multiplied by 2 mm, where 2 mm - this is the standard thickness of putty that you put on the wall.You get the desired amount of filler.To learn number of bags in the performance of work, divide that amount by 25, consider the density ratio, which is listed on the bags, usually it is 0.1.
6
The calculation sheet and tile materials take into account the fact that you have to use a single sheet, and throw scraps.So first count whole number plates and then think over whether dividing the plate into pieces to use both halves (it will greatly reduce the number of waste).

# Tip 2: How to calculate the capacitance

hard to imagine an electrical device in a scheme which is not a capacitor, whose main characteristic is the capacity.In designating the capacitor indicates its rated capacity, while the actual capacity can vary significantly.
Guide
1
capacity describes the ability of a conductor or system of conductors to store electric charge.This ability, in practice, the conductor is used in capacitors.Condenser called two conductors between which an electric field, all the lines of force which starts at one end and a conductor on the other.In a simple capacitor values ​​of the charges on obk4ladkah equal in magnitude but opposite in sign.Electrical capacitance of the capacitor generally equal to the ratio value of the charge on one of the plates to the potential difference between them:

C = q / U

per unit capacity adopted 1 farad, that is, the capacity of the capacitor, in which the presence of a charge in 1 pendant differencepotential between the electrodes is 1 volt.The shape of the conductive surfaces distinguish planar, cylindrical and spherical capacitors.
2
capacity flat capacitor is calculated as follows:

C = εS / d,

where ε - absolute dielectric permittivity, S - area of ​​the conductor plate, d - distance between the plates.
3
capacity cylindrical capacitor is calculated by the formula:

C = 2πεl / ln (b / a),

where l - length of the condenser, b - the radius of the outer cylinder, a - radius of the inner cylinder.
4
capacity spherical capacitor is calculated as follows:

C = 4πε / (1 / a - 1 / b),

where a - radius of the inner sphere, b - the radius of the outer sphere.
5
capacity two-wire line is calculated according to the formula:

C = πεl / ln (d / a),

where l - length of wire, d - the distance between the axes of the wires, a - their radius
6
To increase the capacitance of the capacitor connected to the battery.The batteries are connected in parallel plate capacitors, that is positively charged obkladkisoedinyayutsya in one group, the other negative.Battery electric capacity capacitors connected in parallel is the sum capacity of all capacitors.

C = C1 + C2 + C3 + ... + Cn

In a series connection of capacitors connected oppositely charged electrode.Electrical capacitance capacitors connected in series is equal to the sum of their reciprocal feedback capacitance.

C = 1 / (1 / C1 + 1 / C2 + 1 / C3 + ... + 1 / Cn)
Sources:
• how to calculate the capacitance of the capacitor

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