Resistors in Parallel - Parallel Connected Resistors

Laws of parallel connection

The voltage is the same everywhere in a parallel connection.

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The total current is the sum of all partial currents:

I_t =  I₁  +  I₂ + … +  I_n         (1)

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Determination of the total resistance:

I_t   =  I₁  +  I₂ + … +  I_n          Eq.(1) divided by V
V       V       V           V

according to the Law of Ohm follows

1      =      1   +   1   +    …   +     1  
R_t           R₁       R₂                      R_n 

Special case 1: All the resistors are of the same size

1      =    n       bzw.     R_t = R / n
R_t          R

Special case 2: Only 2 resistors are in parallel

1      =      1   +  1      =   R2 + R1
R_t             R₁     R₂          R2 * R1

Form reciprocal and it follows:

R_t   =   R2 *  R1    
            R1  +   R2