Voltage Division in Series Circuit of Resistors

       Consider a series circuit of tow resistors R1 and R2 connected to source V volts.

       As tow resistors are connected in series, the current flowing through both the resistors is same, i.e. I. Then applying KVL, we get,
                                                                 V= I R1 +I R


       Total voltage applied is equal to the sum of voltage drops VR1 and VR2 across R1 and R2 respectively.
...                     VR1 = I R


Similarly,             VR2  = I R

 
       So this circuit is a voltage divider circuit.
Key point : So in general, voltage drop across any resistor, or combination of resistors, in a series circuit is equal to the ratio of that resistance value to the total resistance, multiplied by the source voltage.

Example : Find the voltage across the three resistances shown in the Fig.
 Solution : 

Key point : It can be seen that voltage across any resistance of series circuit is ratio of that resistance to the total resistance, multiplied by the source voltage.

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