Find the value of R_eq or (Rab ) in the following network.

CONCEPT:

• Resistance: The obstruction offered to the flow of current is known as resistance. It is denoted by R.
• When two or more resistances are connected one after another such that the same current flows through them then it is called resistances in series.
• The equivalent resistance in series combination is will be
  Rser = R1 + R2 + R3
  
• When the terminals of two or more resistances are connected at the same two points and the potential difference across them is equal then it is called resistances in parallel.
• The net resistance/equivalent resistance(R) of resistances in parallel is given by:
  \(\frac{1}{R} = \frac{1}{{{R_1}}} + \frac{1}{{{R_2}}}\)
   

EXPLANATION:

Given that,

Here, 10 Ω is connected parallel with 40 Ω and 20 Ω is connected parallel with 5 Ω and both parallel connections are connected together.

Hence, equivalent resistance (R) will be given as,

R = (20 || 5) + (10 || 40) Ω

or, R = \(\frac{20\times 5}{20+5}+\frac{10\times 40}{10+40}=12\ Ω\)