Question

Two condensers of capacities $1\mu F$ are connected in series and the system is charged to $120$volts. Them the P.D. on $1\mu F$ capacitor (in volts) will be

• A. $40$
• B. $60$
• C. $80$
• D. $120$

Answer 1

The correct option is A $40$

Two condensers of capacities $=1\mu F$

Charge$=120V$

Find P.D of $1\mu F$ capacitor willbe

Solution

Since it will said initially a $10\mu F$ cap had a voltage of $120V$the charge on that cap will be $1\mu C$ when another cap is added series to it, charge does not change so that product of capacitance and voltage remains same.

$C_1{V}_1=C_2{V}_2$

Here $C_1=1\mu F$ and $V_1=120V$

$V_2=40V$ when $C_2=3\mu F$

$1\times 120=3\times V_2{V}_2=40V$