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) $4\pi {\epsilon }_{0}a$

(3) $4\pi {\epsilon }_{0}b$

(4) $4\pi {\epsilon }_{0}a\left(\frac{{\displaystyle b}}{{\displaystyle b-a}}\right)$

The intensity of electric field at a point between the plates of a charged capacitor 

(1) Is directly proportional to the distance between the plates

(2) Is inversely proportional to the distance between the plates

(3) Is inversely proportional to the square of the distance between the plates

(4) Does not depend upon the distance between the plates

In a spherical condenser radius of the outer sphere is R. The difference in the radii of the outer and inner sphere is x. Its capacity is proportional to

(1) $\frac{xR}{(R-x)}$

(2) $\frac{x(R-x)}{r}$

(3) $\frac{R(R-x)}{x}$

(4) $\frac{R}{x}$

A parallel plate condenser with oil between the plates (dielectric constant of oil K = 2) has a capacitance C. If the oil is removed, then capacitance of the capacitor becomes 

(1) $\sqrt{2}C$

(2) 2C

(3) $\frac{C}{\sqrt{2}}$

(4) $\frac{C}{2}$

Two identical charged spherical drops each of capacitance C merge to form a single drop. The resultant capacitance is -

(1) Equal to 2C

(2) Greater than 2C

(3) Less than 2C but greater than C

(4) Less than C

A 12pF capacitor is connected to a 50V battery. How much electrostatic energy is stored in the capacitor ?

(1) 1.5 × 10^–8 Joule

(2) 2.5 × 10^–7 Joule

(3) 3.5 × 10^–5 Joule

(4) 4.5 × 10^–2 Joule

The capacity of a parallel plate condenser is 15 μF, when the distance between its plates is 6 cm. If the distance between the plates is reduced to 2 cm, then the capacity of this parallel plate condenser will be?
1. 15 μF
3. 30 μF
4. 45 μF
5. 60 μF

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