• Resistor resistance to the circuit and reduces the flow of electrical current.
• Reduce ? Depends on value of Resistor.    
• These values are measured in ohms

Ohm’s Law

• V = voltage, I = current, R = resistance

• V= 12v, R = 600 Ohm

• I = 12 V/600 Ohm

• I = 0.02 A = 20 mA (milli Ampere)

• So the current in the circuit is 20 mA.

• R = 600 Ohm , I = 3 Ma

• V= 600 x 3 = 1.8 v

• Resistors have different wattage ratings (W = V X I)

• Quarter Watt , Half Watt, 1 Watt, 2 Watt etc.

Tolerance of a Resistor

Tolerance = value of resistor x value of tolerance band 

Gold = ± 5%

Silver = ± 10 %

None = ± 20%

Types of Resistor

1. Carbon
2. Wire wound.
3. Thin Film .
4. Carbon Film.
5. Metal Film.
6. Thick Film.
7. Metal Oxide .

And then

1. Variable
2. Fixed

And then

1. NTC
2. PTC

Surface Mount Device

The size of SMD resistors is indicated by a numerical code, such as 0603. This code contains the width and height of the package. So, the imperial code 0603 indicates a length of 0.060″ and a width of 0.030″

Series Vs. Parallel

Series = >  R = r1+r2+r3+………rn

Parallel => 1/R = 1/r1 + 1/r2+…..1/rn

Kirchhoff’s Laws

The voltage around a loop equals the sum of every voltage drop in the same loop for any closed network and equals zero

COLOUR CODE

5 Band Resistor Color Code

6 Band Resistor Color Code

Kirchhoff’s Voltage Law

The algebraic sum of all voltages in a loop must equal zero.