GAT PYQ 2024 Mock Test – I – Q1

An infinite combination of resistors, each
having resistance R = 4 W, is given below.
What is the net resistance between the points A
and B? (Each resistance is of equal value, R = 4)
A
B
RR
R
R
RR R
R
¥

• 0 W
• 22 + 5 Ω
• 25 + Ω
• ∞ W

Equivalent Resistance,
y = R + R||y
=> y = R + (R*y)/(R+y)
=> y = (R^2 + R*y + R*y)/(R+y)
=> Ry + y^2 = R^2 + 2Ry
=> y^2 – 4y – 16 = 0
=> Req or y = 2 + 2*sqrt(5) ohm