An electron is accelerated through a potential difference of 45.5 volt. The velocity acquired by it is (in ms^-1)

• 10⁶

• zero

• 4 × 10⁶

• 4 × 10⁴

A spherical drop of capacitance 1 μF is broken into eight drops of equal radius. Then, the capacitance of each small drop is

• $\frac{1}{2} \mathrm{\mu F}$

• $\frac{1}{4} \mathrm{\mu F}$

• $\frac{1}{8} \mathrm{\mu F}$

• 8 μF

An uncharged sphere of metal is placed inside a charged parallel plate capacitor. The lines of force will look like

Effective capacitance between A and B in the figure shown is (all capacitances are in µF)

• $\frac{3}{14} \mathrm{\mu F}$

• $\frac{14}{3} \mathrm{\mu F}$

• 21 μF

• 23 μF

An air filled parallel plate condenser has a capacity of 2 pF. The separation of the plates is doubled and the interspace between the plates is filled with wax. If the capacity is increased to 6 pF, the dielectric constant of wax is

• 2

• 3

• 4

• 6

A parallel plate air capacitor has a capacitance C. When it is half filled with a dielectric of dielectric constant 5, the percentage increase in the capacitance will be 

• 400 %

• 66.6 %

• 33.3 %

• 200 %

A gang capacitor is formed by interlocking a number of plates as shown in figure. The distance between the consecutive plates is 0.885 cm and the overlapping area of the plates is 5 cm. The capacity of the unit is

• 1.06 pF

• 4 pF

• 6.36 pF

• 12.72 pF

Two identical capacitors each of capacitance 5 µF are charged to potentials 2 kV and 1 kV respectively. Their -ve ends are connected together. When the +ve ends are also connected together, the loss of energy of the system is

• 160 J

• zero

• 5 J

• 1.25 J

79.

A parallel plate capacitor with air as the dielectric has capacitance C. A slab of dielectric constant K and having the same thickness as the separation between the plates is introduced so as to fill one-fourth of the capacitor as shown in the figure. The new capacitance will be

               

• $\left(\mathrm{K} + 3\right) \frac{\mathrm{C}}{4}$

• $\left(\mathrm{K} + 2\right) \frac{\mathrm{C}}{4}$

• $\left(\mathrm{K} + 1\right) \frac{\mathrm{C}}{4}$

• $\frac{\mathrm{KC}}{4}$

The potential of a large liquid drop when eight liquid drops are combined is 20 V. Then the potential of each single drop was

• 10 V

• 7.5 V

• 5 V

• 2.5 V