CURRENT
What is current?
Current is types of energy. A flow of current is
called current.
AC (Alternating Current)
AC is short for alternating current.
This means that the direction of current flowing in a circuit is constantly
being reversed back and forth. This is done with any type of AC current/voltage
source.
The
electrical current in your house is alternating current. This comes from power
plants that are operated by the electric company. Those big wires you see
stretching across the countryside are carrying AC current from the power plants
to the loads, which are in our homes and businesses.
DC (Direct Current)
DC is short for Direct
current. The battery we have been using for a current/voltage source
generates direct current, which simply means the current flows in only one
direction.
As long
as electrons are flowing through the atoms of the circuit, work is being done.
We can see that work is being done in this circuit because it lights the light
bulb. The actual amount of electrons that are flowing is determined by the type
and size of the battery as well as by the size and type of the light bulb. We
could reverse the polarity of the battery by switching the contacts (wires),
and the current would flow in the opposite direction and the bulb would
still light.
Either way the battery is
connected to the circuit, current can only flow in one direction. Direct current (DC) can also be
generated by means other than batteries. Solar cells, fuel cells, and even some
types of generators can provide DC current.
Resistance
Resistor is an
electrical component that reduces the electrical current. The resistor's
ability to reduce current is called resistance and is measured in units of Ohms
[Ω].If we make an analogy to water flow in pipes, the resistor is a thin pipe
that reduces the water flow.
A resistor is a
device that resists, or limits, the flow of electric charge through itself, in
the same way that a narrow or partially blocked pipe resists the flow of water
through friction. The power source driving the current through the circuit
generates electrical energy, and the resistor converts that
electrical energy into heat energy.
Resistance
is Show by “R” and Symbol is
Ohms
1000 Ohms = 1 Kilo Ohms
1000 Kilo Ohms = 1 Mega Ohms
1 Mega Ohms
= I Gega Ohms
Symbol of
Ohms
Types of
Resistance
1. Normal Resistance (4 Band, 5 Band)
a. Series Resistance
One by one continually of resistance is
called series resistance. The total equivalent resistance of resistors in
series RTotal is the sum of the resistance
values:
RTotal = R1+ R2+ R3+...
So when you add resistors in parallel, the total
resistance increases.
(2600 Ohm’s 5% +) + (6600 Ohm’s 5% +)
Total Value this resistance is 9200 Ohms 10% +
b. Parallel Resistance
Two Resistances of the both sides joining
is called parallel resistance. The total value find in the quarters (25%)
result given. So when you add resistors in parallel, the total resistance decreases.
4 Band Color Code Resistance Table
Color
|
Band I
|
Band II
|
Band III
|
Band IV
|
Silver
|
-
|
-
|
X 0.01
|
10% +, -
|
Golden
|
-
|
-
|
X 0.1
|
5% +, -
|
Black
|
-
|
0
|
-
|
Not
Use
On
Band
IV
|
Brown
|
1
|
1
|
0
|
Red
|
2
|
2
|
00
|
Orange
|
3
|
3
|
000
|
Yellow
|
4
|
4
|
0000
|
Green
|
5
|
5
|
00000
|
Blue
|
6
|
6
|
000000
|
Valuate / Purple
|
7
|
7
|
0000000
|
Gray
|
8
|
8
|
00000000
|
White
|
9
|
9
|
000000000
|
5 Band Color Code Resistance Table
Color
|
Band I
|
Band II
|
Band III
|
Band IV
|
Band V
|
Silver
|
-
|
-
|
-
|
X 0.01
|
10% +, -
|
Golden
|
-
|
-
|
-
|
X 0.1
|
5% +, -
|
Black
|
-
|
0
|
0
|
-
|
-
|
Brown
|
1
|
1
|
1
|
0
|
1%
|
Red
|
2
|
2
|
2
|
00
|
2%
|
Orange
|
3
|
3
|
3
|
000
|
-
|
Yellow
|
4
|
4
|
4
|
0000
|
-
|
Green
|
5
|
5
|
5
|
00000
|
0.5%
|
Blue
|
6
|
6
|
6
|
000000
|
0.10%
|
Valuate / Purple
|
7
|
7
|
7
|
0000000
|
-
|
Gray
|
8
|
8
|
8
|
00000000
|
0.05%
|
White
|
9
|
9
|
9
|
000000000
|
-
|
No Color
|
-
|
-
|
-
|
|
20%
|
Variable
Resistance is three legs & no color coding. Variable Resistance is show
(VR). Leg 01 & 02 is Value input & leg 03 Value out.
3.Micro Resistance or Micro Resistance Chip
0
|
Fuse
|
100
|
10 Ohms
|
101
|
100 Ohms
|
102
|
1000 Ohms
|
103
|
10000 Ohms
|
104
|
100000 Ohms
|
200
|
20 Ohms
|
201
|
200 Ohms
|
202
|
2000 Ohms
|
203
|
20000 Ohms
|
300
|
30 Ohms
|
302
|
3000 Ohms
|
303
|
30000 Ohms
|
470
|
47 Ohms
|
