A circuit is replaced by its Thevenin's equivalent to finding current through a certain branch. If V_TH = 10 V and R_TH = 20 Ω, the current through the branch:

Thevenin's Theorem:

Thevenin’s Theorem states that “Any linear circuit containing several voltages and resistances can be replaced by just one single voltage in series with a single resistance connected across the load".

Thevenin's equivalent circuit:

\(I = {V_{th} \over R_{th}+R}\)

Calculation:

Given, V_th = 10 V

R_th = 20 Ω 

\(I = {10 \over 20+R}\)

• If R = 0 Ω, then the value of current is 0.5 A
• If R > Ω, then the value of current is less than 0.5 A

Hence, option 1 is correct.