RESISTOR

RESISTOR

basics
a simple ohm law

v= I R

• resistance reduces or limits currents
• divides the voltage
•  resistance is measured in ohms (Ω)
• converts electrical energy into heat which is dissipated into the air where this principle is used in a iron box resistor is used as a heating element

what is a current

• move of electrons inside a atom ie electrons when charged move towards a hole to ocupy it ,it constitutes to a current
•  current is measured in ampere (A)
• current is always directed from positive to negative terminal
• or entering of current is always positive
• where as leaving end is always negative

what is a voltage

• potential difference between the two ends
• measured in volt(v)

TYPES OF RESISTANCE

1. Fixed resistance-resistance value is fixed

• carbon film tolerance(5%,10%)
• metal film(1%,2%)
• wire wound

1. variable resistance -resistance r so small to write values therefore colored need color coding

table

RESISTANCE COLOR CODING

 

 

 

 

 

 here colors are

1.  brown  1st value
2. black     2nd value
3. orange  multiplier
4. yellow tolerance

values taken from the table

brown 1

black   0

orange 1000

yellow +or - 3%

 10*10^3 tolerance +or - 3%