Transcript Measurements of tensions and current constant and to bake

DC and AC volatage and current
Preparing and measuring.
Presented by
Kamil Wojnarowski and Sebastian Białecki
February 2012
U is the symbol of voltage known as electrical potential
difference or electric tension (denoted ∆V and measured
in volts, or joules per coulomb)which is the potential
difference between two points — or the difference in
electric potential energy per unit charge between two
points.
It is an important parameter of a source of
energy which determines the amount of
electric work to do.
Electric current - tidied up (directed) move of
electric charges.
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Direct current or DC electricity is the continuous movement of
electrons from an area of negative (−) charges to an area of positive
(+) charges through a conducting material such as a metal wire.
A DC circuit is necessary to allow the current or steam of electrons
to flow. Such a circuit consists of a source of electrical energy (such
as a battery) and a conducting wire running from the positive end of
the source to the negative terminal.
Alternating current (AC) electricity is the type of electricity
commonly used in homes and businesses throughout the world.
While direct current (DC) electricity flows in one direction through a
wire, AC electricity alternates its direction in a back-and-forth
motion. The direction alternates between 50 and 60 times per second,
depending on the electrical system of the country.
Voltage is measured using
voltmeters and electric current is
measured using an ammeter
The accuracy of the conducted measurement depends on many
factors which it is possible to divide in so-called mistakes and
measuring uncertainties.
We are dividing measuring errors into three groups:
1. approximation error,
2. mistake of the omission (systematic),
3. mistakes.
Approximation errors result from simplifying conditions of
measurement or from applying rough formulae. When
approximation errors are bigger than measuring uncertainties, then
one should enforce relevant amendments.
Mistakes of the omission (systematic) result from the inaccuracy of used
devices, the false method of measurement or acting with difficulty of
noticeable extrinsic factors. Badly made ruler, badly gauged measure they
will cause, that the result will be systematically smaller or bigger than the
actual value. Detecting the source of systematic errors is difficult and
requires comparing used devices with the standard and the in-depth
analysis of the method of measurement. At exercises performed in the
student laboratory we usually assume that devices are free from
systematic errors.
Mistakes (gross errors) are coming into existence as a result of false
reading out readings, of incorrect writing the result and the like mistakes
are letting easily notice oneself and eliminate, since the received result
differs from other results of measurements of the same size. In further
analysis one should omit results burdened with the gross error.
The project is realized with the finance support of the
European Commission within the
"Longlife learning program".
The presentation was made as a result of the Leonardo
da Vinci project titled "Your future career prospects"
carried out in "Zespół Szkół Zawodowych" no 3 in
Katowice between 2011 and 2013.
The publication reflects the standpoint of the authors
only and neither the European Commission nor the
National Agency bear responsibility for the essential
contents included in the presentation and for the way of
using the enclosed information.