Series Circuit

 The resistors can be combined in two ways to get the desired resistance.

    (1) Series Circuit (combination of resistors in series)

(2) Parallel Circuit (Combination of resistors in parallel)

When two or more resistances are connected end to end so that same current flows through each resistor they are said to be connected in series. Suppose three resistors R₁, R₂ and R₃ are joined in series as shown in figure and let the current passing through them be I.

Let V₁, V₂ and V₃ be the potential difference across each resistor respectively. According to ohm’s law:

              V₁    =    I R₁
V₂    =    I R₂
and     V₃    =    I R₃

If V is the total potential difference between the ends A and D, then

V    =    V₁    +    V₂    +    V₃
or       V    =    I R₁  +    I R₂  +    I R₃

If R_s is the resultant resistance of series circuit, then

V     =    IR_s
or       IR_s   =    I R₁ +  I R₂ + I R₃
or       IR_s   =    I(R₁ +  R₂ + R₃)
or       R_s    =    R₁ + R₂ + R₃

So, when some resistors are joined in series, the total resistance of given series of resistors is equal to the sum total of individual resistors.

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1. What is series circuit?