;
;  ;parallel connection of wires
;               r1 & a1
;             .---------.
;  v & a & r? ^         v
;  -----------.         .-----
;             v r2 & a2 ^
;             .---------.
;
;  ;set voltage & resistance
;  v  = 1  &&  v1=v  &&  v2=v
   r1 = 1
   r2 = 2
;
;  ;get partial & total amperage
;  a1=v1/r1
;  a2=v2/r2
;  a =a1+a2
;
;  ;r-formula
;              v         v       /       1               r1*r2
;  r = v/a = ----- = ---------  /v = ----------------- = -----
;            a1+a2    v     v  /      1     1    r2+r1   r1+r2
;                    --- + ---       --- + --- = -----
;                     r1    r2        r1    r2   r1*r2
;


r = r1*r2/(r1+r2)
