# two parallel plates have charges Q1 and Q2 on them and the capacitance is C.The PD between them is????

Arun Kumar IIT Delhi
8 years ago
Hi Mostafijur,
Let the plates be a,b
$\\ Q_a=Q_1 \\Q_b=Q_2 \\Q_{a,left}+Q_{a,right}=Q_1 \\Q_{b,left}+Q_{b,right}=Q_2 \\Q_{a,left}=Q_{b,right} \\Q_{a,right}+Q_{b,left}=0 \\=>Q_{a,left}=(Q_1+Q_2)/2 \\=>Q_{a,right}=(Q_1-Q_2)/2 \\=>Q_{b,left}=(Q_2-Q_1)/2$
Now the internal two sides will act as capacitor with charge
$\\Q_{b,left} \,or \,Q_{a,right} \\ so,|E|=|Q_{b,left}/C|$
Direction you can find .

Thanks & Regards

Arun Kumar

IIT Delhi