Electrostatic Potential and Capacitance NEET Questions with Solutions

Q: How many questions come from Electrostatic Potential and Capacitance in NEET 2027?

You can expect 1 to 2 questions from this chapter in NEET 2027. The chapter has very high PYQ frequency. Potential of a point charge, capacitor combinations (series and parallel), parallel plate capacitor with dielectric, and energy stored are the most repeated topics.

Q: What is electric potential?

Electric potential V at a point is the work done by an external agent in moving a unit positive charge from infinity to that point against the electric field. SI unit is volt (V), where 1 V equals 1 J per C. For a point charge q at distance r, V equals k q over r. Potential is a scalar; you simply add (with sign) for many charges.

Q: How are electric field and potential related?

E equals minus dV over dr. The field points from high potential to low potential. The negative gradient of V gives the field. If V is constant in some region, E equals 0 there. Equipotential surfaces are always perpendicular to field lines.

Q: What is a capacitor?

A capacitor is a device that stores electric charge and energy. It is made of two conductors separated by an insulator. When connected to a battery, charge plus Q gathers on one plate, minus Q on the other. Capacitance C is defined as Q over V, where V is the potential difference across the plates. SI unit is farad (F).

Q: What is the formula for a parallel plate capacitor?

For two flat plates of area A separated by distance d in vacuum, C equals epsilon_0 A over d. The capacitance increases with bigger plates and decreases with larger separation. Inserting a dielectric of dielectric constant K makes C equals K epsilon_0 A over d.

Q: How do capacitors combine in series and parallel?

Parallel: each capacitor has the same V, so their charges add. C_eff equals C_1 plus C_2 plus C_3. Series: each carries the same charge Q, so their voltages add. 1 over C_eff equals 1 over C_1 plus 1 over C_2 plus 1 over C_3. Series gives a smaller effective C; parallel gives a larger one.

Q: How much energy is stored in a capacitor?

U equals half Q V equals half C V squared equals half Q squared over C. The energy lives in the electric field between the plates. Energy density (energy per unit volume in vacuum) is u equals half epsilon_0 E squared.

Question 1

Potential at distance [math] from a point charge [math] is:

Accepted Answer

[math]

Question 2

The SI unit of capacitance is:

Accepted Answer

Farad

Question 3

A parallel plate capacitor has area [math] and separation [math]. Its capacitance in vacuum is:

Accepted Answer

[math]

Question 4

Two capacitors of 4 µF and 6 µF are connected in series. Equivalent capacitance:

Accepted Answer

2.4 µF

Question 5

Energy stored in a capacitor of capacitance [math] at voltage [math]:

Accepted Answer

[math]

Question 6

A capacitor with vacuum has C₀. Filling the gap with a dielectric of K = 5, capacitance becomes:

Accepted Answer

[math]

Question 7

Two capacitors of 4 µF and 6 µF are in parallel. Equivalent capacitance:

Accepted Answer

10 µF

Question 8

The potential energy of two point charges [math] and [math] separated by [math] is:

Accepted Answer

[math]

Question 9

Inside a region where E = 0, the potential V is:

Accepted Answer

Constant

Question 10

A 5 µF capacitor charged to 100 V stores energy:

Accepted Answer

0.025 J

Question 11

Equipotential surfaces of a uniform field are:

Accepted Answer

Parallel planes perpendicular to E

Question 12

Doubling the plate area and halving the separation, parallel plate capacitance changes by:

Accepted Answer

×4

Question 13

Two charges [math] and [math] are placed [math] apart. Potential at the midpoint:

Accepted Answer

Zero

Question 14

A capacitor is connected to a battery and then a dielectric (K) is inserted. The charge on the capacitor:

Accepted Answer

Becomes K times

Question 15

Three charges [math], [math], [math] are at the vertices of an equilateral triangle of side [math]. Total PE:

Accepted Answer

[math]

Question 16

Three capacitors of 1, 2, 3 µF are connected in series. Equivalent capacitance:

Accepted Answer

6/11 µF

Question 17

A capacitor stores 0.5 mC at 100 V. Its capacitance is:

Accepted Answer

5 µF

Question 18

A parallel-plate capacitor's energy is doubled when the voltage is doubled (capacitance fixed). True or false?

Accepted Answer

False, energy quadruples

Question 19

The potential varies as [math] along the x-axis. The field at x = 1 is:

Accepted Answer

−8 V/m

Question 20

A capacitor stores energy U at voltage V. If voltage is halved (with C fixed), the new energy is:

Accepted Answer

[math]

Question 21

A capacitor is disconnected from the battery, then a dielectric K is inserted. Its energy:

Accepted Answer

Becomes 1/K times

Question 22

Potential at the centre of a square of side [math] with charges [math] at all four corners is:

Accepted Answer

[math]

Question 23

A parallel plate capacitor of 5 pF has voltage 100 V. Charge on each plate:

Accepted Answer

500 pC

Question 24

Two capacitors C and 2C are connected in series across a battery V. The voltage across C is:

Accepted Answer

[math]

Question 25

Work done in moving a charge along an equipotential surface is:

Accepted Answer

Zero

Question 26

Inserting a metal slab (perfect conductor) of thickness [math] into a parallel-plate capacitor with separation [math] changes its capacitance to:

Accepted Answer

[math]

Question 27

Three charges [math], [math], [math] are at the vertices of an equilateral triangle of side [math]. Total PE:

Accepted Answer

[math]

Question 28

A dielectric slab is inserted halfway between the plates of a parallel-plate capacitor (filling half the area). With K = 4, the capacitance becomes:

Accepted Answer

[math]

Question 29

A point charge [math] is at the centre of a hollow conducting spherical shell of inner radius [math], outer radius [math]. Potential at distance [math] where [math]:

Accepted Answer

[math]

Question 30

A 4 µF capacitor at 50 V is connected in parallel to an uncharged 6 µF capacitor. Final common voltage:

Accepted Answer

20 V

Question 31

A spherical conductor of radius [math] has capacitance:

Accepted Answer

[math]

Question 32

Electric field is uniform along the x-axis with magnitude [math]. Potential difference [math] where A is at [math] and B is at [math]:

Accepted Answer

[math]

Electrostatic Potential and CapacitanceNEET Physics · Class 12 · NCERT Chapter 2

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Electrostatic Potential and CapacitanceNEET Physics · Class 12 · NCERT Chapter 2

1NEET 2018EasyPotential at distance r from a point charge q is:

2NEET 2020EasyThe SI unit of capacitance is:

3NEET 2022MediumA parallel plate capacitor has area A and separation d. Its capacitance in vacuum is:

4NEET 2024MediumTwo capacitors of 4 µF and 6 µF are connected in series. Equivalent capacitance:

5NEET 2017MediumEnergy stored in a capacitor of capacitance C at voltage V:

6NEET 2019MediumA capacitor with vacuum has C₀. Filling the gap with a dielectric of K = 5, capacitance becomes:

7NEET 2021MediumTwo capacitors of 4 µF and 6 µF are in parallel. Equivalent capacitance:

8NEET 2023MediumThe potential energy of two point charges q1​ and q2​ separated by r is:

9NEET 2018MediumInside a region where E = 0, the potential V is:

10NEET 2020MediumA 5 µF capacitor charged to 100 V stores energy:

11NEET 2022EasyEquipotential surfaces of a uniform field are:

12NEET 2024MediumDoubling the plate area and halving the separation, parallel plate capacitance changes by:

13NEET 2017MediumTwo charges +q and −q are placed 2a apart. Potential at the midpoint:

14NEET 2019MediumA capacitor is connected to a battery and then a dielectric (K) is inserted. The charge on the capacitor:

15NEET 2021MediumThree charges +q, +q, +q are at the vertices of an equilateral triangle of side a. Total PE:

16NEET 2023MediumThree capacitors of 1, 2, 3 µF are connected in series. Equivalent capacitance:

17NEET 2018EasyA capacitor stores 0.5 mC at 100 V. Its capacitance is:

18NEET 2020MediumA parallel-plate capacitor's energy is doubled when the voltage is doubled (capacitance fixed). True or false?

19NEET 2022MediumThe potential varies as V=4x2+3 along the x-axis. The field at x = 1 is:

20NEET 2024MediumA capacitor stores energy U at voltage V. If voltage is halved (with C fixed), the new energy is:

21NEET 2017MediumA capacitor is disconnected from the battery, then a dielectric K is inserted. Its energy:

22NEET 2019MediumPotential at the centre of a square of side a with charges +q at all four corners is:

23NEET 2021MediumA parallel plate capacitor of 5 pF has voltage 100 V. Charge on each plate:

24NEET 2023MediumTwo capacitors C and 2C are connected in series across a battery V. The voltage across C is:

25NEET 2018MediumWork done in moving a charge along an equipotential surface is:

26NEET 2020MediumInserting a metal slab (perfect conductor) of thickness t into a parallel-plate capacitor with separation d changes its capacitance to:

27NEET 2022MediumThree charges +q, −q, +q are at the vertices of an equilateral triangle of side a. Total PE:

28NEET 2024MediumA dielectric slab is inserted halfway between the plates of a parallel-plate capacitor (filling half the area). With K = 4, the capacitance becomes:

29NEET 2017MediumA point charge q is at the centre of a hollow conducting spherical shell of inner radius a, outer radius b. Potential at distance r where r>b:

30NEET 2019MediumA 4 µF capacitor at 50 V is connected in parallel to an uncharged 6 µF capacitor. Final common voltage:

31NEET 2021MediumA spherical conductor of radius R has capacitance:

32NEET 2023MediumElectric field is uniform along the x-axis with magnitude E. Potential difference VA​−VB​ where A is at x=0 and B is at x=d:

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