The capacity of a parallel plate capacitor with no dielectric substance but with a separation of 0.4 cm is 2 μF. The separation is reduced to half and it is filled with a dielectric substance of value 2.8. The final capacity of the capacitor is 

(1) 11.2 μF

(2) 15.6 μF

(3) 19.2 μF

(4) 22.4 μF

Two insulated metallic spheres of 3 μF and 5 μF capacitances are charged to 300 V and 500V respectively. The energy loss, when they are connected by a wire is 

(1) 0.012 J

(2) 0.0218 J

(3) 0.0375 J

(4) 3.75 J

A charge of 40 μC is given to a capacitor having capacitance C = 10 μF. The stored energy in ergs is 

(1) 80 × 10^–6

(2) 800

(3) 80

(4) 8000

A parallel plate capacitor has plate area A and separation d. It is charged to a potential difference V₀. The charging battery is disconnected and the plates are pulled apart to three times the initial separation. The work required to separate the plates is 

(1) $\frac{3{\epsilon }_{0}A{V}_0^2}{d}$

(2) $\frac{{\epsilon }_{0}A{V}_0^2}{2d}$

(3) $\frac{{\epsilon }_{0}A{V}_0^2}{3d}$

(4) $\frac{{\epsilon }_{0}A{V}_0^2}{d}$

The electric field between the plates of a parallel plate capacitor when connected to a certain battery is E₀. If the space between the plates of the capacitor is filled by introducing a material of dielectric constant K without disturbing the battery connections, the field between the plates shall be 

(1) K E₀

(2) E₀

(3) $\frac{E_0}{K}$

(4) None of the above

If the distance between parallel plates of a capacitor is halved and dielectric constant is doubled then the capacitance 

(1) Decreases two times

(2) Increases two times

(3) Increases four times

(4) Remain the same

If there are n capacitors each of capacitance C in parallel connected to V volt source, then the energy stored is equal to 

1. CV

2. $\frac{1}{2}nC{V}^2$

3. CV²

4. $\frac{1}{2n}C{V}^2$

The unit of electric permittivity is 

(1) Volt/m²

(2) Joule/coulomb

(3) Farad/m

(4) Henry/m

The work done in placing a charge of 8 × 10^–18 coulomb on a condenser of capacity 100 micro-farad is 

(1) 32× 10^–32 Joule

(2) 16 × 10^–32 Joule

(3) 3.1 × 10^–26 Joule

(4) 4 × 10^–10 Joule