Question 166: Electrostatics & Capacitance

Question

A 5 $$\mu $$F capacitor is charged fully by a 220 V
supply. It is then disconnected from the supply
and is connected in series to another
uncharged 2.5 $$\mu $$F capacitor. If the energy
change during the charge redistribution is
$${X \over {100}}J$$ then value of X to the nearest integer is
_____.

Accepted Answer

u
i
= $$\frac{1}{2} $$ $$ 	imes $$ 5 $$ 	imes $$ 10
-6
$$ 	imes $$220
Final common potential
= $$\frac{220	imes 5+0	imes 2.5}{5+2.5} $$ = 220 $$ 	imes $$ $$\frac{2}{3} $$
u
f
= $$\frac{1}{2} $$ $$ 	imes $$ (5 + 2.5)$$ 	imes $$10
-6
$$ 	imes $$ $$\left( 220	imes \frac{2}{3} ight)^{2} $$
$$\Delta $$u = u
i
- u
f
$$ \Rightarrow $$ $$\Delta $$u = Ã¢ÂÂ403.33 ÃÂ 10
Ã¢ÂÂ4
$$ \Rightarrow $$ Ã¢ÂÂ403.33 ÃÂ 10
Ã¢ÂÂ4
= $${X \over {100}}J$$
$$ \Rightarrow $$ X = -4.03
Value of X is approximate 4

Electrostatics & Capacitance

A 5 $\mu F capacitor is charged fully by a 220 V supply. It is then disconnected from the supply and is connected in series to another uncharged 2.5 \mu F capacitor. If the energy change during the charge redistribution is {X \over {100}}J$ then value of X to the nearest integer is _____.

Integer / Numeric Answer Type