Question

The resultant capacity between the points P and Q of the given figure is

• A. $4\mu F$
• B. $\frac{16}{3}\mu F$
• C. $1.6\mu F$
• D. $1\mu F$

Answer 1

Answer: (A)

As seen from the circuit, between $P$ and $Q$ there is a combination of three capacitors.
In this combination two $4\mu F$ capacitors are connected in series and this series connection is connected in parallel to the $2\mu F$ capacitor.
So, effective capacitance of the series combination:
$\frac{1}{C_{\text{eff }}}=\frac{1}{C_1}+\frac{1}{C_2}$
or, $\frac{1}{C_{\text{eff }}}=\frac{1}{4}+\frac{1}{4}$
or, $C_{\text{eff }}=2\mu F$
Now, this $2\mu F$ capacitance comes in parallel with the $2\mu F$ capacitance.
So, effective capacitance of this parallel combination:
$C_{\text{eff }}^{\prime }=C_1+C_2$
or, $C_{\text{eff }}^{\prime }=2\mu F+2\mu F$
or, $C_{\text{eff }}^{\prime }=4\mu F$