If E be the electric field inside a parallel plate capacitor due to Q and -Q charges on the two plates, then electrostatic force on plate having charge -Q due to the plate having charge +Q will be
(1) -QE
(2)
(3) QE
(4)
Capacitors are connected in series across a source of emf 20KV. The potential difference across will be
(1) 5 KV
(2) 15 KV
(3) 10 KV
(4) 20 KV
The equivalent capacitance between A and B is as the given figure:
(1)
(2)
(3)
(4) None of these
A spherical condenser has inner and outer spheres of radii a and b respectively. The space between the two is filled with air. The difference between the capacities of two condensers formed when outer sphere is earthed and when inner sphere is earthed respectively will be
(1) Zero
(2)
(3)
(4)
Two identical capacitors are joined in parallel, charged to a potential V and then separated and then connected in series i.e. the positive plate of one is connected to negative of the other
(1) The charges on the free plates are destroyed
(2) The charges on the free plates are enhanced
(3) The energy stored in the system increases
(4) The potential difference in the free plates becomes 2V
A parallel plate capacitor is made by stacking n equally spaced plates connected alternately. If the capacitance between any two plates is C then the resultant capacitance is
(1) C
(2) nC
(3) (n – 1)C
(4) (n + 1)C
Four plates of equal area A are separated by equal distances d and are arranged as shown in the figure. The equivalent capacity is
(1)
(2)
(3)
(4)
Three capacitors are connected to D.C. source of 100 volts shown in the adjoining figure. If the charge accumulated on plates of C1, C2 and C3 are and qf respectively, then
(1)
(2)
(3)
(4)
Five capacitors of 10 μF capacity each are connected to a d.c. potential of 100 volts as shown in the adjoining figure. The equivalent capacitance between the points A and B will be equal to
(1) 40 μF
(2) 20 μF
(3) 30 μF
(4) 10 μF
Three capacitors of capacitances 3 μF, 9 μF and 18 μF are connected once in series and another time in parallel. The ratio of equivalent capacitance in the two cases will be:
1. 1 : 15
2. 15 : 1
3. 1 : 1
4. 1 : 3