CBSE Questions for Class 12 Medical Physics Electrostatic Potential And Capacitance Quiz 4 - MCQExams.com

Figure shows three points A, B and C in a region of uniform electric field $$\vec E$$. The line AB is perpendicular and BC is parallel to the field lines. Then which of the following holds good. Here $$V_A, V_B$$ and $$V_C$$ represents the electric potential at point A, B and C respectively.
112133.jpg
  • $$V_A=V_B=V_C$$
  • $$V_A=V_B > V_C$$
  • $$V_A=V_B < V_C$$
  • $$V_A > V_B = V_C$$
Find the charge appearing on capacitor of capacitance $$4\;\mu F$$ :

112118_a49a67107dac4f01a5005c60a79d47ce.png
  • $$32\;\mu C$$
  • $$96\;\mu C$$
  • $$12\;\mu C$$
  • $$4\;\mu C$$
A capacitor stores $$60\space\mu C$$ charge when connected across a battery. When the gap between the plates is filled with a dielectric, a charge of $$120\space\mu C$$ flows through the battery. The dielectric constant of the material inserted is :
  • $$1$$
  • $$2$$
  • $$3$$
  • none
In the adjoining figure, capacitor $$(1)$$ and $$(2)$$ have a capacitance $$'C'$$ each. When the dielectric of dielectric constant $$K$$ is inserted between the plates of one of the capacitor, the total charge flowing through battery is :

126546_4c73d3477e6e429f86dafc360280a59d.png
  • $$\displaystyle\frac{KCE}{K+1}\space from\space B\space to\space C$$
  • $$\displaystyle\frac{KCE}{K+1}\space from\space C\space to\space B$$
  • $$\displaystyle\frac{(K-1)CE}{2(K+1)}\space from\space B\space to\space C$$
  • $$\displaystyle\frac{(K-1)CE}{2(K+1)}\space from\space C\space to\space B$$
Four identical plates $$1, 2, 3,$$ and $$4$$ are placed parallel to each other at equal distance as shown in the figure. Plates $$1$$ and $$4$$ are joined together and the space between $$2$$ and $$3$$ is filled with a dielectric of dielectric constant $$k = 2$$. The capacitance of the system between $$1$$ and $$3$$ & $$2$$ and $$4$$ are $$C_1$$ and $$C_2$$ respectively. The ratio $$C_1/C_2$$ is :

126556_f7340aeb538b4c848dcf8b4695a1029b.png
  • $$\displaystyle\frac{5}{3}$$
  • $$1$$
  • $$\displaystyle\frac{3}{5}$$
  • $$\displaystyle\frac{5}{7}$$
A capacitor of capacitance $$C$$ is initially charged to a potential difference of $$V$$ volt. Now it is connected to a battery of $$2V$$ volt with opposite polarity. The ratio of heat generated to the final energy stored in the capacitor will be :
  • $$1.75$$
  • $$2.25$$
  • $$2.5$$
  • $$\dfrac{1}{2}$$
The capacitance of a parallel plate capacitor is $$C$$ when the region between the plate has air. This region is now filled with a dielectric slab of dielectric constant $$k$$. The capacitor is connected to a cell of emf $$E$$, and the slab is taken out
  • charge $$CE(k-1)$$ flows through the cell
  • energy $$E^2C(k-1)$$ is absorbed by the cell
  • the energy stored in the capacitor is reduces by $$E^2C(k-1)$$
  • the external agent has to do $$\displaystyle\frac{1}{2}E^2C(k-1)$$ amount of work to take the slab out
Two capacitors $$C_1$$ and $$C_2$$ are connected in series, assume that $$C_1 < C_2$$. The equivalent capacitance of this arrangement is $$C$$, where
  • $$C < C_1/2$$
  • $$C_1/2 < C < C_1$$
  • $$C_1 < C < C_2$$
  • $$C_2 < C < 2C_2$$
Statement 1: The electrostatic force between the plates of a charged isolated capacitor decreases when dielectric fills whole space between plates.

Statement 2: The electric field between the plates of a charged isolated capacitance decreases when dielectric fills whole space between plates
  • Statement-1 is true, Statement-2 is true and Statement-2 is the correct explanation for Statement-1
  • Statement-1 is true, Statement-2 is true and Statement-2 is NOT the correct explanation for Statement-1
  • Statement-1 is true, Statement-2 is false
  • Statement-1 is false, Statement-2 is true
A capacitor of capacitance $$ 1 \mu F $$ withstands a maximum voltage of 6 kilovolt while another capacitor of $$ 2 \mu F $$ withstands a maximum voltage 4 kilovolt . if the two capacitor are connected in series, the system will withstand a maximum of:
  • 2kV
  • 4kV
  • 6kV
  • 9kV
A parallel plate capacitor has a parallel slab of copper inserted between and parallel to the two plates, without touching the plates. The capacity of the capacitor after the introduction of the copper sheet is:
  • minimum when the copper slab touches one of the plates
  • maximum when the copper slab touches one of the plates
  • invariant for all positions of the slab between the plates
  • greater than that before introducing the slab
A dense sphere of mass $$M$$ is placed at the centre of a circle of radius $$R$$. Find the work done, when a particle of mass $$m$$ is brought from A to B along a circle as shown in the figure.
143568.jpg
  • $$zero$$
  • $$\displaystyle \frac{G M m}{R}$$
  • $$\displaystyle - \frac{G Mm}{R}$$
  • $$\displaystyle \frac{2 G M m}{R}$$
A capacitor of capacitance 10$$\mu$$F is charged by connecting through a resistance of 20 ohm and a battery of 20 V. What is the energy supplied by the battery?
  • Less than 2 m J
  • 2 m J
  • More than 2 m J
  • Cannot be predicted
Potential in electrostatics is analogous to:
  • pressure in gases
  • temperature in thermal physics
  • levels in liquids
  • all of the above
P is a point on an equipotential surface S. The field at P is E.
  • E must be perpendicular to S in all cases.
  • E will be perpendicular to S only if S is a plane surface.
  • E cannot have a component along a tangent to S.
  • E may have a nonzero component along a tangent to S if S is a curved surface.
An electrical charge of $$2$$ $$\mu$$C is placed at the point $$(1, 2, 3)$$. At the point $$(2, 3, 4)$$ the electric field and potential will be :
  • $$6 \times 10^3 NC^{-1}$$ and $$6 \times 10^3 JC^{-1}$$
  • $$6000 NC^{-1}$$ and $$6000 \sqrt{3} JC^{-1}$$
  • $$6 \times 10^3 NC^{-1}$$ and $$3\sqrt{3} JC^{-1}$$
  • none of the above
An air-filled parallel plate capacitor has a capacity $$2 pF$$. The separation between the plates is doubled and the interspace is filled with wax, If the capacity is increased to 6 pF, the dielectric constant of the wax is :
  • $$2$$
  • $$4$$
  • $$3$$
  • $$6$$
In a uniform electric field, equipotential surfaces must :
  • be plane surfaces
  • be normal to the direction of the field
  • be spaced such that surfaces having equal differences in potential are separated by equal distances
  • have decreasing potentials in the direction of the field
Two equal charges A and B each of $$1/3 \times 10^{-6}C$$ are placed 200 cm apart in air. A particle carrying a charge of $$-1/3 \times 10^{-6}C$$ is projected along the perpendicular bisector from the point O midway between A and B with a kinetic energy of $$10^{-3} J$$. Before the particle starts to return it will cover a distance
  • $$1 m$$
  • $$\sqrt{2}$$ m
  • $$\sqrt{3}$$ m
  • $$1/\sqrt{3}$$ m
A capacitor has charge $$50\mu$$ C. When the gap between the plates is filled with glass wool 120 $$\mu $$ C charge flows through the battery. The dielectric constant of glass wool is :
  • $$3.4$$
  • $$1.4$$
  • $$2.4$$
  • none of these
The energy stored in a condenser is in the form of
  • electrostatic energy
  • magnetic energy
  • elastic energy
  • kinetic energy
Potential of point A is?
1750770_bc12415117ba4f419bf4c5e1f3f2c472.png
  • $$3$$V
  • $$6$$V
  • $$9$$V
  • Zero
The capacitance of a parallel-plate capacitor is $$C_0$$ when the region between the plates has air. This region is now filled with a dielectric slab of dielectric constant K. The capacitor is connected to a cell emf $$\varepsilon _1$$ and the slab is taken out.
  • Charge $$\varepsilon C_0(K-1)$$ flows through the cell.
  • Energy $$\varepsilon ^2C_0(K-1)$$ is absorbed by the cell.
  • The energy stored in the capacitor is reduced by $$\varepsilon ^2C_0(K-1)$$.
  • The external agent has to do $$\frac{1}{2}\varepsilon ^2C_0(K-1)$$ amount of work to take the slab out.
A $$1\  mm$$ thick paper of dielectric constant 4 lies between the plates of a parallel-plate capacitor. It is charged to 100 volt the intensity of electric field between the plates of the condenser will be  :
  • 100
  • 100000
  • 400000
  • 25000
A parallel plate condenser is connected to a battery of emf 4 volt. If a plate of dielectric constant 8 is inserted into it, the potential difference on the condenser will be :
  • 32 V
  • 4 V
  • 1/2 V
  • 2 V
The distance between the plates of a parallel plate air condenser is d. if a copper plate of the same area but thickness $$\dfrac d2$$ is placed between the plates then the new capacitance will become :
  • doubled
  • half
  • one fourth
  • remain unchanged
A parallel-plate air capacitor is connected to a battery. The quantities charge, voltage, electric field and energy associated with this capacitor are given by $$Q_0, V_0, E_0$$ and $$U_0$$ respectively. A dielectric slab is now introduced to fill the space between the plates with battery still in connection. The corresponding quantities now given by Q, V, E and U are related with previous ones as :
  • $$V > V_0$$
  • $$U > U_0$$
  • $$Q > Q_0$$
  • $$E > E_0$$
On increasing the plate separation of charged condenser its energy :
  • remains unchanged
  • decreases
  • increases
  • none of these
On removing the dielectric from a charged condenser, its energy
  • increase
  • remains unchanged
  • decreases
  • none of these
When dielectric medium of constant k is filled between the plates of a charged parallel-plate condenser, then the energy stored becomes, as compared to its previous value, 
  • $$K^{-3} times$$
  • $$K^{-2} times$$
  • $$K^{-1} times$$
  • $$K times$$
Which of the following units is not equivalent to Farad?
  • $$CV^2$$
  • $$J/V^2$$
  • $$Q^2/J$$
  • $$Q/V$$
The capacitance of a condenser is $$20 \mu F$$ and it is charged to a potential of 2000 V. The energy stored in it will be :
  • zero
  • 40 J
  • 80 J
  • 120 J
A capacitor of capacitance C is connected to battery of emf $$V_0$$. Without removing the battery, a dielectric of strength $$\varepsilon _r$$ is inserted between the parallel plates of the capacitor C, then the charge on the capacitor is :
  • $$CV_0$$
  • $$\varepsilon _rCV_0$$
  • $$\dfrac{CV_0}{\varepsilon _r}$$
  • none of these
The net charge on a condenser is :
  • infinity
  • q/2
  • 2q
  • zero
A parallel plate condenser with plate separation d is charged with the help of battery so that $$V_0$$ energy is stored in the system. The battery is now removed. a plate of dielectric constant k and thickness d is placed between the plates of condenser. The new energy of the system will be :
  • $$V_0 k^{-2}$$
  • $$k^2 V_0$$
  • $$V_0 k^{-1}$$
  • $$k V_0$$
The energy stored between the plates of a condenser in not represented by :
  • $$U=\dfrac{CV^2}{2}$$
  • $$U=2qV$$
  • $$U=\dfrac{q^2}{2C}$$
  • $$U=\dfrac{qV}{2}$$
Which of the following is correct statement :
  • Equipotential lines are always perpendicular to the electric field
  • Work done for moving a charge along the conducting surface (closed and containing charge) very close to it may be negative or positive
  • Electric field may cross each other
  • None of the above
A battery of 100 V is connected to series combination of two identical parallel-plate condensers. If dielectric of constant 4 is slipped between the plates of second condenser, then the potential difference on the condensers will respectively become :
  • 80 V, 20 V
  • 75 V, 25 V
  • 50 V, 80 V
  • 20 V, 80 V
The energy stored between the plates of a condenser in not represented by :
  • $$U=\dfrac{CV^2}{2}$$
  • $$U=2qV$$
  • $$U=\dfrac{q^2}{2C}$$
  • $$U=\dfrac{qV}{2}$$
The capacitance of a charged condenser is C and energy stored on account of charge on it is U, then the quantity of charge on the condenser will be :
  • $$\sqrt{2UC}$$
  • $$\sqrt{\frac{UC}{2}}$$
  • $$2UC$$
  • zero
The energy acquired by a charged particle of $$4 \mu C$$ when it is accelerated through a potential difference of 8 Volt will be :
  • $$3.2\times 10^{-7} J$$
  • $$3.2\times 10^{-5} J$$
  • $$2\times 10^{-6} J$$
  • $$2\times 10^{-5} J$$
Three condensers each of capacitance 2 F, are connected in series. The resultant capacitance will be :
  • 6 F
  • 5 F
  • 2/3 F
  • 3/2 F
When two condensers of capacitance $$1\mu F$$ and $$2\mu F$$ are connected is series then the effective capacitance will be :
  • $$\dfrac{2}{3}\mu F$$
  • $$\dfrac{3}{2}\mu F$$
  • $$3\mu F$$
  • $$4\mu F$$
What will be area of pieces of paper in order to make a paper condenser of capacitance $$0.04 \mu F$$, if the dielectric constant of paper is $$2.5$$ and its thickness is $$0.025 mm$$ ?
  • $$1m^2$$
  • $$2\times 10^{-3} m^2$$
  • $$4.51\times10^{3} m^2$$
  • $$10^{-3} m^2$$
In a charged capacitor, the energy resides in :
  • the positive charges
  • both the positive and negative charges
  • the field between the plates
  • around the edge of the capacitor plates
The capacitance of a parallel plate capacitor in air is $$2\ \mu F$$. If a dielectric medium is placed between the plates then the potential difference reduces to $$\dfrac{1}{6}$$ of the original value. The dielectric constant of the medium is :
  • $$6$$
  • $$3$$
  • $$2.2$$
  • $$4.4$$
A slab X is placed between the two parallel isolated charged plates as shown in the figure. If $$E_p$$ and $$E_q$$ denotes the intensity of electric field at P and Q, then :

146923_b49561fef618478bbe8bd62635d53716.png
  • $$E_p$$ is reduced by the presence of X, if X is metallic
  • $$E_q$$ is increased by presence of X, if X is dielectric
  • $$E_q$$ is in the opposite sense to $$E_p$$, if X is dielectric
  • $$E_q$$ is zero, if X is metallic
The capacitance of parallel-plate capacitor is $$4\mu F$$. If a dielectric material of dielectric constant 16 is placed between the plates then the new capacitance will be :
  • $$1/64 \mu F$$
  • $$0.25 \mu F$$
  • $$64 \mu F$$
  • $$40 \mu F$$
A parallel plate capacitor is connected to a battery. The plates are pulled apart with a uniform speed. If $$'x'$$ is the separation between the plates, then the time rate of change of electrostatic energy of the capacitor is proportional to :
  • $$x^{2}$$
  • $$x$$
  • $$x^{-1}$$
  • $$x^{-2}$$
A condenser is charged to a potential difference of 200 volts as a result of which it gains charge of 0.1 coulomb. When it is charged then the  energy released will be :
  • 1 J
  • 2 J
  • 10 J
  • 20 J
0:0:1


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