FMDC 2012 Paper
Q10. If in a parallel plate capacitor we insert a metal sheet of half the thickness as compared with the spacing between the plates of the capacitor, the capacitance becomes...?
C) 2 C
D) 4 C
E) 0.5 C
When the metal plate is inserted we get the following situation:
The original capacitance was:
C = ∈A/d
New capacitance of each capacitor will be :
C' = ∈A/d/4 = 4 ∈A/d = 4C
Now we have to identical capacitors in series, so there equivalent capacitance will be 2C .
1/Ceq = 1/C1 + 1/C2 for series combination of capacitors.