

Series combination- In a series combination of resistors, resistors are connected end to end.
The resultant resistance is the sum of all the resistances in the circuit.
If there are four resistors in circuit, R1, R2,R3 and R4, and R is their resultant resistance.
R = R1+R2+R3+R4
Parallel combination- If all the given resistors are connected between two common terminals(ends) then this type of combination is called parallel combination.
Resultant resistance for this combination is-
1/R = 1/R1+1/R2+1/R3+1/R4

