ELECTRONICS- RESISTERS-series¶llel

ELECTRONIC COMPONENTS

RESISTOR 

Resistor is used to control current flow in a circuit. Usually using resistors are carbon resistors. When current flows through a resistor heat is produced according to Joules law H=I*I*R*T, I=intensity of current,R=resistance,T=time

value of resistor 

The first two colour lines gives the value of resistance and the third one gives the power of multiplier of 10.fourth line gives the tolerance

For eg: In the figure 1, the first red color gives the value 2,second line black gives 0,third red is multiplier of 10(10^2) gold color line gives tolerance +5 or -5.Then the value is 20*100,=2000 ohms,ie 2kilo ohm

CONNECTING RESISTANCES IN A CIRCUIT
1. SERIES COMBINATION        2. PARALLEL COMBINATION 3. MIXED COMBINATION

SERIES COMBINATION

 If three resistor are 2 ohms, 3 ohms, 4 ohms connected series to a 3v battery. What is the total resistance? what is the current in the circuit?
 In series combination effective resistance R=R1+R2+R3
R=2+3+4=9
By ohms law potential difference V=IR
I=V/R  =3v/9 ohms=1/3 A

PARALLEL COMBINATION

If R1=10 ohms , R2=15 ohms are connected in parallel in a circuit with a 12V battery. What is the effective resistance?
1/R=1/R1+1/R2
1/R=1/10+1/15
R=6 ohms

MIXED COMBINATION

EQUATION FOR COMBINATION OF RESISTERS