Question

In the circuit given below, the equivalent capacitance is ______________

(a) \(\frac{C}{4}\)

(b) \(\frac{5C}{13}\)

(c) \(\frac{5C}{2}\)

(d) 3C

This question was addressed to me in unit test.

This is a very interesting question from Series-Series Connection of Two Port Network in chapter Two-Port Networks of Network Theory

Answer 1

Correct choice is (b) \(\frac{5C}{13}\)

Easy explanation: The equivalent capacitance by applying the concept of series-parallel combination of the capacitance is,

\(\frac{1}{C_{EQ}} = \frac{1}{C} + \frac{1}{C} + \frac{1}{5C/3}\)

= \(\frac{1}{C} + \frac{1}{C} + \frac{3}{5C}  = \frac{1}{C}(\frac{5+5+3}{5})\)

Or, CEQ = \(\frac{5C}{13}\)

123 c Energy delivered during talk time

E = ∫ V(t)I(t) dt

Given, I (t) = 2 A = constant = 2 ∫ V(t)dt

= 2 × Shaded area

= 2 × \(\frac{1}{2}\) × (10 + 12) × 60 × 10

= 13.2 kJ.