Capacitors-DPP7(ISC)

The capacitance of a parallel plate condenser does not depend on

• Area of the plates

• Medium between the plates

• Distance between the plates

• Metal of the plates

An uncharged capacitor is connected to a battery. On charging the capacitor

• All the energy supplied is stored in the capacitor

• Half the energy supplied is stored in the capacitor

• The energy stored depends upon the capacity of the capacitor only

• The energy stored depends upon the time for which the capacitor is charged

The capacitance of an air capacitor is  $15\mu f$  the separation between the parallel plates is $6mm$  . A copper plate of  thickness 3mm is introduced symmetrically between the plates.  The capacitance now becomes 

•  $5\mu f$  

•  $7.5\mu f$  

•  $22.5\mu f$  

•  $30\mu f$  

The expression for the capacity of the capacitor formed by compound dielectric placed between the plates of a parallel plate capacitor as shown in figure, will be (area of plate=A )

• $\frac{\epsilon_oA}{\left(\frac{d_1}{k_1}+\frac{d_2}{k_2}+\frac{d_3}{k_3}\right)}$

• $\frac{\epsilon_oA}{\left(\frac{d_1+d_2+d_3}{k_1+k_2+k_3}\right)}$

• $\frac{\epsilon_oA\left(k_1k_2k_3\right)}{d_1d_2d_3}$

• $\epsilon_o\left(\frac{Ad_1}{k_1}+\frac{Ad_2}{k_2}+\frac{Ad_3}{k_3}\right)$

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

• $\sqrt{2\ }C$

• 2C

• $\frac{C}{\sqrt{2\ }}$

• $\frac{C}{2}$

A parallel plate capacitor is first charged and then a dielectric slab is introduced between the plates. The quantity that remains unchanged is

• Charge C

• Potential V

• Capacity C

• Energy U

Two protons A and B are placed in space between plates of a parallel plate capacitor charged upto V volts (See fig.) Forces on protons are  $F_A$    and $F_B$   , then 

•  $F_A>F_B$  

•  $F_A<F_B$  

•  $F_A=F_B$  

• Nothing can be said

While a capacitor remains connected to a battery and dielectric slab is applied between the plates, then

• Potential difference between the plates is changed

• Charge flows from the battery to the capacitor

• Electric field between the plates increases

• Energy store in the capacitor decreases

Putting a dielectric substance between two plates of condenser, capacity, potential and potential energy respectively

• Increase, decrease, decrease

• Decrease, increase, increase

• Increase, increase, increase

• Decrease, decrease, decrease

If the distance between the plates of parallel plate capacitor is halved and the dielectric constant of dielectric is doubled, then its capacity will

• Increase by 16 times

• Increase by 4 times

• Increase by 2 times

• Remain the same