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Sliding contact of a potentiometer is in the middle of the potentiometer wire having resistance Rₚ=1 Ω as shown in the figure. An external resistance of Rₑ=2 Ω is connected via the sliding contact. The electric current in the circuit is

Asked in JEE Main 22nd Jan 1st Shift 2025 · Potentiometer measurements

Figure: Potentiometer measurements
Answer: (2) 1.0 A

Step-by-step solution

Step 1: the slider is at the middle, so it splits the wire into two halves of 0.5 Ω each.

Step 2: Rₑ runs from the slider back to one end of the wire, so it sits in parallel with that half.

Rₚₐᵣₐₗₗₑₗ=(0.5×2)/(0.5+2)=1/(2.5)=0.4 Ω.

Step 3: that combination is in series with the other half.

Rₜₒₜₐₗ=0.4+0.5=0.9 Ω.

Step 4: I=V/(Rₜₒₜₐₗ)=(0.9)/(0.9)=1.0 A.

Why the other options are wrong

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