electrostatic potential and capacitance neet questions || electrostatic potential and capacitance jee questions

   Dear students numericals of electrostatic potential and capacitance neet questions and electrostatic potential and capacitance jee questions aiims important questions have been collected at one place to get you all prepared for your neetaiims ,jee main, advance exams as well as cbse board exams and other board exams. Visit my nawendu classes youtube channel for more help.

1.  1. Two point charges 4$\mu $C and -2 $\mu $C are separated by a distance of 1 m in air. Calculate at what point on the line joining the two charges is the electric potential zero ? 
             C.B.S.E. 2007
      Answer- 2/3m  from 4 $\mu $C 
2. The electric potential at the surface of an atomic nucleus (Z = 50) of radius 9.0 x ${{10}^{-15}}$m 
       JIPMER 1998 
Answer- 8 x ${{10}^{6}}$  V
3. An electric charge ${{10}^{-3}}$ $\mu $C is placed at the origin (0, 0) of X – Y co-ordinate system, Two points A and B are situated at (√2, √2) and (2, 0) respectively. The potential difference between the points A and B will be
        AIEEE 2007 
Answer- Zero
4. Four electric charges +q, +q,-q and -q are placed at the corners of a square of side 2 L (see figure). The electric potential at point A, mid-way between the two charges +q and +q is
        CBSE AIPMT 2011 
Four electric charges

Answer- $\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{2q}{L}\left( 1-\frac{1}{\sqrt{5}} \right)$
5. Four point charges-Q,-q, 2q and 2Q are placed, one at each corner of the square. The relation between Q and q for which the potential at the centre of the square is zero, is
 Answer- Q= -q
6. A, B and C are three points in a uniform electric field. The electric potential is
       NEET 2013 
A, B and C

Answer- maximum at B
7. A hollow metal sphere of radius 10 cm is charged such that the potential on its surface is 80 V. The potential at the center of the sphere is
 Answer- 80V
8. A conducting sphere of radius R  is given a charge Q. The electric potential and the electric field at the center of the sphere respectively are 
      CBSE AIPMT 2014 
Answer- $\frac{Q}{4\pi {{\varepsilon }_{0}}R}$  and zero
9. The electric potential at a point in free space due to a charge Q coulomb is Qx${{10}^{11}}$ V. The electric field at that paint is  
Answer- $4\pi {{\varepsilon }_{0}}Q$ x${{10}^{22}}$ V/m
10. A cube of side b has a charge q at each of its vertices. Determine the potential and electric field due to this charge array at the center of the cube.
Answer- Potential = $V=\frac{4q}{\sqrt{3}\pi {{\varepsilon }_{0}}b}$ , Electric field= 0
11. Two concentric spheres of radii R and r have similar charges with equal surface charge densities ($\sigma $). What is the electric potential at their common center ? 
Answer- $\frac{\sigma }{{{\varepsilon }_{0}}}(R+r)$
12. As per this diagram a point  charge +q is placed at the origin O. Work done in taking another point charge - Q from the point A   [coordinates (0,a)] to  another point B  [Coordinates (a, 0)]  along the straight Path AB is .
       CBSE AIPMT 2005 
Answer- Zero
13.  charges  + q and -q are placed at points A and B respectively Which are a distance 2L apart, C Is the mid-point between A and B .
 The work done in moving a charge  +Q  along the semicircle CRD is 
 CBSE AIPMT 2007, AIIMS 2017 
charges  + q and -q
Answer- $\frac{-qQ}{6\pi {{\varepsilon }_{0}}L}$
14. Two points P and Q are maintained at the potential of 1V and -4V, respectively. The work done in moving 100 electrons from P to Q is
       AIEEE 2009  
Answer-  2.24 x${{10}^{-16}}$ J
15. A ball of mass 1 g and charge ${{10}^{-8}}$ C moves from a point A where potential is 600 V to the point B Where potential is zero. Velocity of the ball at the point B is 20 cm/s. The velocity of the ball at the point A will be 
       AIIMS 2009 
Answer- 16.7cm/s
16. A proton is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 kV, its kinetic energy will be 
       AIIMS 2003  
Answer- 1KeV
17. Two spheres A and B of radius a and b respectively are at the same potential. The ratio the surface charge density of A and B is
Answer- b/a
18. An infinite thin plane sheet of charge density ${{10}^{-8}}$${{m}^{-2}}$ is held in air.
How far apart are two equipotential surfaces, whose p.d. is 5 volt ?
       C.B.S.E. 2003 
 Answer- 8.85 x ${{10}^{-3}}$ m 
19.Two point charges A and B of value + 15 $\mu $C and + 9 $\mu $C are kept 18 cm
apart in air. Calculate the work done when charge B is moved by 3 cm
towards A.
       C.B.S.E. 2000  
Answer- 1.35 J 
20. There are four point charges +q, -q, +q and -q are placed at the corners A, B, C, and D respectively of a square of side a. The potential energy of the system is  $\frac{1}{4\pi {{\varepsilon }_{0}}}$  times   
        AIIMS 2013 

four point charges

Answer- $\frac{{{q}^{2}}}{a}(-4+\sqrt{2})$
21. A charged particle ‘q’ is shot towards another charged particle ‘Q’ which is fixed, with a speed ‘V’. It approaches ‘Q’ up to a closed distance r and then  returns. If q  where  given a speed of 2v the closest distance of approach would be
         AIEEE 2004 
 Answer- r/4
22. Two charges ${{q}_{1}}$ and ${{q}_{2}}$ are placed 30 cm apart, as shown in the figure. A third charge ${{q}_{3}}$ is moved along the arc of a circle of radius 40 cm from C to D. The change in the potential energy of the system is  $\frac{{{q}_{3}}}{4\pi {{\varepsilon }_{0}}}k$ , where k is
          CBSE AIPMT 2005 
are placed 30 cm apart,

Answer- 8${{q}_{2}}$
23. An electric dipole of moment p is lying along a uniform electric field E. The work done in rotating the dipole by 90° is
          CBSE AIPMT 2006 
 Answer- pE
24. Capacitance  of a spherical conductor with radius 1 m is
          AIEEE 2002 
Answer- 1.1 x ${{10}^{-10}}$ F
25. A spherical drop of capacitance 1$\mu $F is broken into eight drops of equal radius . Then, the capacitance of each small drop is  
          AIIMS 2012 
Answer- 1/2 $\mu $F
26. In a parallel plate capacitor with air between the plates, each plate has an area of 6 × ${{10}^{-3}}$ ${{m}^{2}}$ and the distance between the plates is 3 mm. Calculate the capacitance of the capacitor.
(a) If this capacitor is connected to a 100 V supply, what is the charge on each plate of the capacitor?
(b) Explain what would happen if   3 mm thick mica sheet (of dielectric constant = 6) were inserted between the plates, (1) while the voltage supply remained connected.
                                              (2) after the supply was disconnected.  
Answer- (a)18 pF, 1.8 × ${{10}^{-9}}$ C
              (b)(1)V = 100 V, C = 108 pF, Q = 1.08 × ${{10}^{-8}}$ C
               (2)Q = 1.8 × ${{10}^{-9}}$ C, C = 108 pF, V = 16.6 V
27. A parallel plate condenser with oil (dielectric constant 2) between the plates has capacitance C. If oil is removed, the capacitance of capacitor becomes
         CBSE AIPMT 1999 
Answer- C / 2
28. A parallel plate capacitor with air between the plates has capacitance of 9pF. The separation between its plates is ‘d’ the space between the plates is now filed with two dielectrics. One of the dielectric has dielectric constant k1 = 3 and thickness d/3 while the other one has dielectric constant k2 = 6 and thickness 2d/3. Capacitance of capacitor is now
          AIEEE 2008 
Answer- 40.5 pF
29. The capacitance of a parallel plate condenser is 10 $\mu $ F, when the distance between its plates is 8 cm.   If the distance between plates is reduced to 4 cm then the capacity of this
 parallel plate condenser will be 
          CBSE PMT 2001 
Answer- 20 $\mu $ F
30. A parallel plate capacitor with air between the plates has a capacitance of 8 pF (1pF = ${{10}^{-12}}$ F). What will be the capacitance if the distance between the plates is reduced by half, and the space between them is filled with a substance of dielectric constant 6?
Answer- 96 pF
31. In a parallel plate capacitor, the distance between the plates is d and potential difference across plates is V. Energy stored per unit volume between the plates of capacitor is 
           CBSE AIPMT 2001 
 Answer- $\frac{1}{2}\frac{{{\varepsilon }_{0}}{{V}^{2}}}{{{d}^{2}}}$
32.The work done in placing a charge of 8 x ${{10}^{-18}}$ coulomb on a condenser of
capacity 100 $\mu $ F is 
            AIEEE 2003 
Answer- 32 x ${{10}^{-32}}$ J
 33. If the potential of a capacitor having capacity 6  $\mu $ F is increased from 10 V to 20 V, then increase in its energy will be
Answer- 9 x ${{10}^{-4}}$J
34. If there are n capacitors in parallel connected to V volt source, then the energy stored is equal to
AIEEE 2002 
Answer- $\frac{1}{2}nC{{V}^{2}}$  
35. A 4$\mu $F capacitor is charged to 400 V and then its plates are joined through a resistance of 1 k$\Omega $ .The heat produced in the resistance is  
             CBSE AIPMT 1988 
Answer- 0.32 J
36. The energy required to charge a parallel plate condenser of plate separation d and plate area of cross-section A such that the uniform electric field between the plates E, is
             CBSE AIPMT 2008 
 Answer-  ${{\varepsilon }_{0}}{{E}^{2}}Ad$  
37. A parallel plate condenser has a uniform electric field E (V/m) in the space between the plates. If the distance between the plates is d(m) and area of each plate is A(m2 ), the energy (joule) stored in the condenser is
              CBSE AIPMT 2011 
 Answer-  $\frac{1}{2}{{\varepsilon }_{0}}{{E}^{2}}Ad$  
38. A parallel plate air capacitor has capacity C. distance of separation between plates is d and potential difference V is applied between the plates. Force of attraction between the plates of the parallel plate air capacitor is
              CBSE AIPMT 2015 
 Answer-  $\frac{C{{V}^{2}}}{2d}$
39. A parallel plate capacitor has an electric field of ${{10}^{5}}$ V/m between the plates. If the charge on the capacitor plates is 1$\mu $C, the force on each capacitor plate is  
              AIIMS 2017 
Answer- 0.05N
40. A charged oil drop of mass 2.5 x ${{10}^{-7}}$ kg is in space between the two plates, each of area 2 x ${{10}^{-2}}$ ${{m}^{2}}$ of a parallel plate capacitor. When the upper plate has a charge of 5 x${{10}^{-7}}$ C and the lower plate has an equal negative charge, the oil remains stationary. The charge of the oil drop is (Take, g = 10m/${{s}^{2}}$) 
              AIIMS 2010 
Answer- 8.85x${{10}^{-13}}$ C
41. A 600 pF capacitor is charged by a 200 V supply. It is then disconnected from the supply and is connected to another uncharged 600 pF capacitor. How much electrostatic energy is lost in the process?
Answer-6 × ${{10}^{-6}}$ J
42. A capacitor is charged by connecting a battery across its plates. It stores energy U. Now the battery is disconnected and another identical capacitor is connected across it, then the energy stored by both capacitors of the system Will be 
               CBSE AIPMT 2000 
Answer- U/2
43.Two capacitors C and C/2 are connected to a battery of V volts, as shown below .The work done in charging both the capacitors fully is 
 CBSE AIPMT 2007 , AIIMS 2017 

Two capacitors

44.The effective capacitance between points X and Y of figure shown is
               CBSE AIPMT 1999 

effective capacitance

Answer- 6$\mu $F
45. A capacitor of 2$\mu $F is charged as shown in the figure. When the switch S is turned to position 2, the percentage of its stored energy dissipated  is 

             NEET 2016 


Answer-  80%  

46. 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 $c{{m}^{2}}$ . The capacity of the unit is  

           AIIMS 2011 

Answer.- 4pF

47. Three plates of Common surface area A are connected as shown in figure. 


The effective capacitance will be  

           AIIMS 2013 

Answer-\[2A{{\varepsilon }_{0}}/d\] 

48. In the circuit shown in the figure, the potential difference across the 4.5 $\mu $F capacitor is    

     AIIMS 2010 

Answer- 8V

49. A network of four capacitors of ${{C}_{1}}$=C , ${{C}_{2}}$=2C , ${{C}_{3}}$=3C  and ${{C}_{4}}$=4C  are connected to a battery as shown in the figure. 


     The ratio of the  charges on ${{C}_{2}}$  and ${{C}_{3}}$  is

            AIIMS 2009 

Answer- 3/22

50. A series combination of ${{n}_{1}}$ capacitors each of value ${{C}_{1}}$, is charged by a source of potential difference 4V. When another parallel combination of ${{n}_{2}}$ capacitors, each of value ${{C}_{2}}$, is charged by a source of potential difference V,  it has the same (total) energy stored in it, as the first combination has. The value of ${{C}_{2}}$ in term of ${{C}_{1}}$  is then

          CBSE AIPMT 2010 

Answer- $\frac{16{{C}_{1}}}{{{n}_{1}}{{n}_{2}}}$   

51. A 40 $\mu $F capacitor in a defibrillator is charged to 3000 V. The energy stored in the capacitor is sent through the patient during a pulse of duration 2 ms.  The power delivered to the patient is

           AIIMS 2004  

Answer- 90KW

52. Two material having the dielectric constants K1 and K2 are filled between two Parallel plates of a capacitor. Where area of each plate is A and the distance between the plates is d.

Answer- $\frac{A{{\varepsilon }_{0}}({{K}_{1}}+{{K}_{2}})}{2d}$

53. Minimum number of 80$\mu $F and 250 V capacitors are used to make a combination of 16$\mu $F and 1000 V are

              AIIMS 1996 

Answer- 32

# Assertion  and Reason
Direction -Read the Assertion and Reason carefully to mark the correct
Option from those given below
(a)Both Assertion and Reason are true and Reason is the correct explanation of
(b)Both Assertion and Reason are true but Reason is not the correct explanation of
(c)Assertion is true but Reason is false

(d)Both Assertion and Reason are false

54. Assertion-Net electric field inside a conductor is 0

      Reason-Charge is present on the surface of conductor.

            AIIMS 2018 


55. Assertion- The lighting conductor at the top of high building has sharp pointed ends

      Reason-The surface density of charge at sharp points is very high resulting in setting up of electric wind. 

             AIIMS 2005 


56. Assertion- A metallic shield in form of a hollow shell may be built to block an electric field.

      Reason -In a hollow spherical shield, the  electric field inside it is zero at every point.                       AIIMS 2001


57. (a) Two materials having the dielectric constants k1 and k2 are filled between two parallel plates of a capacitor .Where area of each plate is A. and the distance between the plates is d.

The capacity of the capacitor is

               AIIMS 2001

Answer- $\frac{A{{\varepsilon }_{0}}({{k}_{1}}+{{k}_{2}})}{2d}$

58.  A parallel-plate capacitor of area A, plate separation d and capacitance C is filled with four dielectric materials having dielectric Constants k1 ,k2 ,k3 and k4 as shown in the figure below. If a single dielectric material is to be used to have the same capacitance C in this capacitor, then its dielectric constant k is given by

                 NEET 2016 

Answer- $\frac{2}{3}[\frac{{{k}_{1}}{{k}_{4}}}{{{k}_{1}}+{{k}_{4}}}+\frac{{{k}_{2}}{{k}_{4}}}{{{k}_{2}}+{{k}_{4}}}+\frac{{{k}_{3}}{{k}_{4}}}{{{k}_{3}}+{{k}_{4}}}]$

59. Electric field inside a parallel plate capacitor is 100 V/m and dielectric constant inside it is 5.5. Then, the value of polarization is 

              AIIMS 2018 

Answer- 450

60. In free space, a particle A of charge 1 $\mu $C is  held fixed at a point P. Another particle B of the same charge and mass 4$\mu $g  is kept at a distance of 1 mm from  P. If B is released, then its velocity at a distance of 9 mm from P is  

             IIT Main 2019. 10 April ll 

Answer- 20000 m/s

61. The electric field in a region is given by  E=(Ax+B)$\widehat{i}$  where E is in N/C and x is in meters. The values of constants are A = 20 SI unit and B = 10 SI unit. If the potential at x = 1 is V1 and that at x = - 5 is V2, then V1 -V2 is

              IIT Main2019, 8 April II  

Answer- 180V

62. Three charges Q, +q and +q are placed at the vertices of a right angle isosceles triangle as shown below. The net electrostatic energy Of   the configuration is zero, if the value of Q is                     IIT Main 2019, 11 Jan I 

Three charges

Answer- $\frac{-\sqrt{2q}}{\sqrt{2}+1}$

63. Assume that an electric field E= 30 ${{x}^{2}}\widehat{i}$  exists in space. Them the potential difference VA - V0 , where V0 is the potential at the origin and VA the potential at x = 2 m is 

              IIT 2014 Main 

Answer- -80J

64. An alpha particle of energy 5 MeV is scattered through 180° by a fixed uranium nucleus. The distance of closest approach is of the order of 

              IIT 1981, 2M  

Answer- ${{10}^{-12}}$ cm

65. A point charge q moves from a point P to a point S along the path PQRS in a uniform electric field $\overrightarrow{E}$ along positive direction of x-axis. Calculate work done in this process, when co-ordinates of P, Q, R, S are (a, b, 0),(2a, 0, 0), (a, -b, 0) and (0, 0, 0) respectively.


 Answer- -q E a 

No comments

Theme images by belknap. Powered by Blogger.