Wednesday 6 May 2015

Basics of electricity : Sources DC - DC

1 - Basics of electricity

1. Atomic Structure:
To understand the current nature we know that (knowledge high school) all the elements are formed from atoms and each atom of a substance is composed of two parts
- A nuclear between positively charged particles called protons and neutral particles called Neutron electricity.
- The Electron (e) negative charge moving around the nucleus.
- Normally the atoms have electrically neutral state means of Proton Nuclear equal number of electrons on the outside but when external factors such as pressure, temperature, static friction, the effects of magnetic fields. ., the electron in the outermost layer may be separated from the orbit to become free electrons.
- When an atom loses one or more electrons, they are missing electrons and become cations and vice versa when an atom receive one or more electrons, they become negative ions.

2. Current nature and its direction.
When the electron concentration at high densities they generate up charge effects
- Electric current is moving stream of charged particles such as electron, ion.
- Afternoon conventional electrical currents go from positive to negative (opposite to the direction of electron motion - going from negative to positive)

3. Effect of electric current:
When a current flows through the electric conductor experiment as follows:


We see that electricity has created a magnetic field to deflect around the magnet, while the reverse current flow from the well redirect => as the magnet bias in the opposite direction.
- Power flows through the bulb as a bulb light and heat Siang
- Current flow through the engine motor rotates the rotary mechanical energy generated
- When we loaded the poles of the accumulator battery and electric current modified work of power ..
Such currents have effects that thermal effects, effects on function, the effects of magnetic fields and chemical effects on performance.


2 - current and DC voltage

1. According to current:
As characterizing quantity of electrical current intensity or specific to the number of electrons passing through the section of the conductor in a unit of time - is the first symbol
- DC current is moving in a line a certain direction from positive to negative by convention or a line moving in one direction of the free electrons.

Units of amperage is Ampe and multiples:




  • Kilo Ampere = 1000 Ampere


  • Mega Ampere Ampere = 1000.000


  • Mili Ampere = 1/1000 Ampere


  • Micro Amps = 1 / 1000.000 Ampere

2. Voltage:
When the electron density irregularities in the two focus points A and B, if we connect a wire from A to B will appear lines of electrical charges moving from place to place, high density, low-density, as So they called two points A and B have different voltage and voltage difference is the voltage.
- The voltage at point A is called U A
- The voltage at point B is called U B.
- The difference in voltage between two points A and B is called the voltage U AB
U AB = U A - U B
- The unit of voltage is Vol denoted U or E, unit voltage multiples are


  • Kilo Vol (KV) = 1000 Vol


  • Mili Vol (mV) = 1/1000 Vol


  • Micro Vol = 1 / 1000.000 Vol


Voltage can be compared to the height of a water bottle, if two pitchers have different heights, when connecting a hose will have average water flows from high to lower average, the two pitchers have height together, there is no water flowing through the pipes. Electric current is the same if two points have voltage gulf generates electric current through a wire connected to the two points from high voltage to low voltage and if two points are equal, the voltage electric current in the wire will = 0


3 - The fundamental laws

1. Law hug
Slim law is an important law that we need to Comfort Me

Amperage of a circuit section is proportional to the voltage at both ends of the circuit and inversely proportional to the resistance of the circuit there.

The formula: I = U / R in which

  • I was amperage, measured in Ampere (A)

  • U is the voltage at both ends of the circuit, in Vol (V)

  • R is the resistance of the circuit, in hug

2. Law for the circuit hugging
Connected in series circuits:
In a more resistive circuits connected in series, the voltage at both ends of the circuit with the total pressure drop across the resistor.




  • As the diagram above, U = U1 + U2 + U3


  • By law we have U1 = hug I1 x R1, R2 U2 = I2 x,
    U3 = I3 x R3 but the circuit is connected in series I1 = I2 = I3


  • Pressure drop across the resistor => proportional to the resistance.
    Parallel circuits
    In the circuit with many parallel resistor, the current intensity is equal to the sum of the current through the resistor and voltage drop across the resistor is the same:





  • Circuit U1 = U2 = above U3 = E


  • I = I1 + I2 + I3 and U1 = I1 x R1 = I2 = I3 x x R2 R3


  • Amperage inversely proportional to the resistance.

3. Power and capacity:
* Power.
When current flows through the device as bulb => as light bulbs, running through the engine => rotary motors such as electric line was born of. Public electrical power called, denoted W, in practice we often use Wh, kWh (kilo-watt hour)
Power calculation formula is:

W = U x I xt




  • Where W is the power measured in June (J)


  • U is the voltage measured in Vol (V)


  • I is the current measured in Ampere (A)


  • t is time in seconds (s)

* Capacity.
The capacity of the power line is the power consumption for one second, the capacity is calculated by the formula
P = W / t = (U. I .t) / t = U .I

By law we have P = UI hug = U 2 / R = RI 2

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