Electric current
In Chapter Electrostatic Discharge ye have learned that an electric charge can move from one place to another.
For example, if you touch objects negatively charged, then the electrons will move from it to your body.
The amount of electric charge electric current is caused by the movement of electrons electrons flow through a point in electric circuits every time.
Flash you see is actually also the transfer of electrons.
However, can you turn the lights on electricity by harnessing the charged object or lightning?
Likely can not be, because the lamp requires the electron flow continuously.
In this chapter you will learn ways to make the electrons can flow continuously as well as ways to control the flow of electrons.
If the light is connected with the poles of the battery through the wire, then formed a circuit that does not have the base and tip.
This circuit is called a closed circuit or circuits. In this state the light is on. It showed in a closed circuit in the flow of electric charge.
The flow of electric charge is called electric current. The direction of electric current in the wire from the battery positive pole to the negative pole of the battery. Direction of the electric current in a closed circuit shown in
(A) The electric current occurs in a closed circuit,
(B) The flow of electric charge does not occur in open circuit
A large electric current is expressed by a strong electric current, symbolized by I. Strong electrical current is the amount of electric charge through a conductor cross-section of each second.
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| physics formula |
with
q = electric charge .............................. coulomb (C)
t = time ........................................... seconds (s)
I = current strength ...................................... ampere (A)
So, 1 A = 1 C / s. Note that 1 mA = 0.001 A and 1 microampere (uA) = 0.000001 A.
Strong electric current was measured using ammeters. As for the current strength of small, galvanometer is used as a tool to measure it. Note stringing strong ammeters to measure the electrical currents in the Figure below
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| Picture: (a) How to measure the electrical current strength, (b) the circuit diagram. |
Example
Strong currents on an electrical circuit of 200 mA. How large is the electric charge flowing in the circuit every minute?
Note: strong currents, I = 200 mA = 200 × 0,001 A = 0.2 A
time, t = 1 min = 60 s
Asked: electric charge that flows, q?
answer
q = I × t
A q = 0.2 × 60 s
= 12 As = 12 C
Thus, the electric charge that flows is 12 C.
switches
When the day before the evening, you turn on the electric lights. How do I turn on the electric light? You press a button and the lights on a wall switch. Remember, the lamp lights indicate the presence of an electric current.
Electrical currents occur in a closed circuit. Thus, the switch is used to make electrical circuit into a closed or open. Note the function switch in the Figure below
There are two types of switches, the switches manually and automatically. Switches manually close or open the electric circuit with the help of hand.
Switch to turn on the lights, switch blades on the picture above, an example of a manual switch. While the automatic switch works with the help of electronic equipment.
Examples of automatic switch is a switch to turn on traffic lights and a switch to turn on the street lights.
so his physics formula
P = E / t
Where :
P = Power
E = Energy in units of Joules
t = time in units of seconds
In the calculation formula, Electrical Power is usually denoted by the letter "P" which stands for Power. While the International Units (SI) Electricity is abbreviated by W. Watt Watt is equal to one joule per second (Watt = Joule / sec
Watt derived unit frequently encountered of which are as follows:
1 miliWatt = 0.001 Watt
1 kilowatt = 1,000 Watt
1 megawatts = 1,000,000 Watt
Formula Power
The general formula used to calculate the Power in an Electric Circuits are as follows:
P = V x I
Or
P = I2R
P = V2 / R
Where :
P = Power in units of Watts (W)
V = Voltage with the unit of Volt (V)
I = Power Lines with the unit Ampere (A)
R = Barriers to the unit Ohm (Ω)
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