question_answer

In the figure a potential of + 1200 V is given to point A and point B is earthed, what is the potential at the point P [MP PMT 2004]

A)                                                      100 V

B)                    200 V

C)                    400 V

D)                    600 V

Correct Answer: C

Solution :

           Given circuit can be reduced as follows In series combination charge on each capacitor remain same. So using Q = CV Þ \[{{C}_{1}}{{V}_{1}}={{C}_{2}}{{V}_{2}}\] Þ \[3\,(1200-{{V}_{p}})=6({{V}_{P}}-{{V}_{B}})\] Þ \[1200-{{V}_{p}}=2{{V}_{p}}\]                (Q \[{{V}_{B}}=0)\] Þ 3Vp = 1200   Þ \[{{V}_{p}}=\text{ 4}00volt\]