Question

In the circuit given below, the value of RL for maximum power transfer is ___________

(a) 2.4 Ω

(b) 2.6 Ω

(c) 2.8 Ω

(d) 3.0 Ω

Answer 1

The correct option is (c) 2.8 Ω

Easiest explanation: Using Y-∆ transformation,

RAB = (9+9 || 6) || (9||6)

= (18 || 6) || (9 || 6)

=(left(frac{18×6}{18+6} ight) || left(frac{9×6}{9+6} ight))

= 4.5 || 3.6

= (frac{4.5×3.6}{4.5+3.6}) = 2.8 Ω.