Calculate Equivalent Resistance Of Following Combinations Of Resistors R1 R2 R3 R4

Calculate the equivalent resistance of the following combinations of resistors r1, r2, r3, r4.


Since r3 and r4 are in parallel   

∴ Equivalent resistance R1 of this combination is given by

1/R1 = 1/r3 + 1/r4 = r4 + r3/r3r4

Or R1 = r3r4/r3 + r4

Now r1, r2 and R1 are in series

∴ Equivalent resistance R of the whole combination is

R = r1 + r2 + r3r4/r3 + r4 = (r1 + r2)(r3 + r4) + r3r4/r3 + r4 Ω