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 R₂ 

       Total voltage applied is equal to the sum of voltage drops V_R1 and V_R2 across R₁ and R₂ respectively.

.^..                     V_R1 = I R₁ 

Similarly,             V_R2  = I R₂ 

 

       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.