Point charges +4q, - q and +4q are kept on the X -axis at point x = 0 and x = 2a respectively.
1
only -q is in stable equilibrium
2
all the charges are in stable equilbrium
3
all of the charges are in unstable equilibrium
4
none of the charges is in equilibrium
Official Solution
Correct Option:
(3)
At the present position all the charges are in equilibrium. But when they displaced slightly from their present position, they do not return back. So, they are in unstable equilibrium position.
02
PYQ 1995
easy
physicsID: neet-ug-
Two metallic spheres of radii 1 cm and 2 cm are given charges and respectively. If they are connected by a conducting wire, the final charge on the smaller sphere is
1
2
3
4
Official Solution
Correct Option:
(4)
The correct answer is D: Radii of sphere cm = m ; m and charges on sphere; and C. Common potential (V)
= Therefore final charge on smaller sphere = C.
03
PYQ 1995
medium
physicsID: neet-ug-
A charge q is placed at the centre of the line joining two exactly equal positive charges The system of three charges will be in equilibrium, if q is equal to
1
- Q
2
Q/2
3
Q/4
4
#NAME?
Official Solution
Correct Option:
(3)
For equilibrium of charge Q, the force of repulsion due to similar charges Q should be balanced by the force of attraction due to charge q and
or or or .
04
PYQ 1995
medium
physicsID: neet-ug-
There is an electric field E in x-direction. If the work done on moving a charge of 0.2 C through a distance of 2 m along a line making an angle 60 with x-axis is 4 J, then what is the value of E?
1
5 N / C
2
20 N/ C
3
N / C
4
4 N / C
Official Solution
Correct Option:
(2)
Charge (q) = 0.2 C; Distance (d) = 2 m; Angle and work done (W) = 4 J. Work done in moving the charge (W) = or, E = = 20 N / C.
05
PYQ 1996
easy
physicsID: neet-ug-
The energy stored in a capacitor of capacity C and potential V is given by
1
2
3
4
Official Solution
Correct Option:
(4)
Answer (d)
06
PYQ 1996
easy
physicsID: neet-ug-
A point charge + q is placed at the centre of a cube of side . The electric flux emerging from the cube is
1
2
3
zero
4
Official Solution
Correct Option:
(4)
Electric flux emerging from the cube does not depend on size of cube. Total flux =
07
PYQ 1998
easy
physicsID: neet-ug-
A point Q lies on the perpendicular bisector of an electrical dipole of dipole moment p. If the distance of Q from the dipole is r (much larger than the size of the dipole), then the electric field at Q is proportional to
1
and
2
p and
3
and
4
p and
Official Solution
Correct Option:
(4)
he electric field at a point on equatorial line (perpendicular bisector) of dipole at a distance r is given by, E = where 2 a = length of dipole r > > a) i, e., E p and E .
08
PYQ 1999
easy
physicsID: neet-ug-
When air is replaced by a dielectric medium of constant K, the maximum force of attraction between two charges separated by a distance
1
increases K times
2
remains unchanged
3
decreases K times
4
increases times
Official Solution
Correct Option:
(3)
In air the force of attraction between two charges is In dielectric medium the force of attraction between two charges is
\frac{1}{4 \pi K \epsilon_{0}} \frac{ q _{1} q _{2}}{ r ^{2}}=\frac{ F _{ a }}{ K }
Thus, force decreases K-times.
09
PYQ 1999
easy
physicsID: neet-ug-
What is the effective capacitance between points X and y?
1
12 F
2
18 F
3
24 F
4
6 F
Official Solution
Correct Option:
(4)
Reconstruction of circuits gives -
10
PYQ 2000
medium
physicsID: neet-ug-
A capacitor is charged with a battery and energy stored is . After disconnecting battery another capacitor of same capacity is connected in parallel with it. Then energy stored in each capacitor is:
1
2
3
4
Official Solution
Correct Option:
(2)
After connecting with another capacitor
∴Energy on each capacitor = = =
So, the correct option is (B):
11
PYQ 2000
easy
physicsID: neet-ug-
A charge Q is situated at the corner of a cube, the electric flux passed through all the six faces of the cube is
1
2
3
4
Official Solution
Correct Option:
(2)
As at a comer, 8 cubes can be placed symmetrically, flux linked with each cube (due to a charge Q at the comer) will be . Now for the faces passing through the edge A, electric field E at a face will be parallel to area of face and so flux for these three faces will be zero. Now as the cube has six faces and flux linked with three faces (through A) is zero, so flux linked with remaining three faces will be Hence, electric flux passed through all the six faces of the cube is
12
PYQ 2000
easy
physicsID: neet-ug-
Electric field at centre O of semicircle of radius a having linear charge density given as
1
2
3
4
Official Solution
Correct Option:
(3)
Considering symmetric elements each of length at A and B, we note that electric fields perpendicular to PO are cancelled and those along PO are added. The electric field due to an element of length along PO.
Net electric field at O
13
PYQ 2001
medium
physicsID: neet-ug-
Energy per unit volume for a capacitor having area A and separation d kept at potential difference V is given by
1
2
3
4
Official Solution
Correct Option:
(1)
Energy density =
14
PYQ 2001
medium
physicsID: neet-ug-
A dipole of dipole moment is placed in uniform electric field then torque acting on it is given by
1
2
3
4
Official Solution
Correct Option:
(2)
When an electric dipole is placed in a uniform electrical field , the torque on the dipole is given by
15
PYQ 2002
medium
physicsID: neet-ug-
A capacitor of capacitance is charged to a potential and then connected in parallel to an uncharged capacitor of capacitance .The final potential difference across each capacitor will be
1
2
3
4
Official Solution
Correct Option:
(2)
When a charged capacitor of capacitance is connected in parallel to an uncharged capacitor of capacitance , the charge is shared between them till both attain the common potential which is given by, common Potential
16
PYQ 2003
medium
physicsID: neet-ug-
Three capacitors each of capacity 4µF are to be connected in such a way that the effective capacitance of 6µF. This can be done by
1
connecting all of them in a series
2
connecting them in parallel
3
connecting two in series and one in parallel
4
connecting two in parallel and one in series
Official Solution
Correct Option:
(3)
CAB = (2 + 4)µF = 6µF
17
PYQ 2004
medium
physicsID: neet-ug-
A bullet of mass 2 g is having a charge of 2 µC. Through what potential difference must it be accelerated, starting from rest, to acquire a speed of 10 m/s?
1
50 kV
2
5V
3
50 V
4
5kV
Official Solution
Correct Option:
(1)
To accelerate a bullet of mass 2 g and charge 2 µC from rest to acquire a speed of 10 m/s, it must be accelerated through a potential difference of 5 kV.
18
PYQ 2004
medium
physicsID: neet-ug-
The unit of permittivity of free space ε0 is
1
Newton metre2 / Coulomb2
2
Coulomb2 /Newton metre2
3
Coulomb2 / (Newton metre)2
4
Coulomb/Newton metre
Official Solution
Correct Option:
(2)
The unit of permittivity of free space ε₀ is Coulomb² / (Newton meter)².
19
PYQ 2004
medium
physicsID: neet-ug-
An electric dipole has the magnitude of its charge as and its dipole moment is . It is placed in a uniform electric field . If its dipole moment is along the direction of the field, the force on it and its potential energy are respectively
1
and minimum
2
and
3
zero and minimum
4
and maximum
Official Solution
Correct Option:
(3)
The total force on dipole is zero because F = q E is applied on each charge but in opposite direction. The potential energy is U = which is minimum when and are parallel.
20
PYQ 2005
medium
physicsID: neet-ug-
Two charges q1 and q2 are placed 30 cm apart, as shown in the figure. A third charge q3 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 ,where k is:
A network of four capacitors of capacity equal to C1=C,C2=2C,C3=3C and C4=4C are connected to a battery as shown in the figure. The ratio of the charges on C2 an C4 is
1
2
3
4
Official Solution
Correct Option:
(2)
Equivalent capacitance for three capacitors C1,C2 and C3 in series is given by
=
=
= =
Charge on capacitors (C1,C2 & C3) in series
= V =
Now, Charge on capacitor C4=C4V=4CV
=
= =
Therefore, the correct option is (B):
22
PYQ 2006
medium
physicsID: neet-ug-
A parallel plate air capacitor is charged to a potential difference of V volts. After disconnecting the charging battery the distance between the plates of the capacitor is increased using an insulating handle. As a result the potential difference between the plates:
1
decreases
2
does not change
3
becomes zero
4
increases
Official Solution
Correct Option:
(4)
Area of the capacitor is represented by A, and the distance between the plates is represented by d.
Capacitance of a parallel plate capacitor
The capacitance C of the capacitor diminishes as the distance between its plates increases. The potential difference between the plates V increases as capacitance decreases.
So, the correct option is (D): increases
23
PYQ 2006
medium
physicsID: neet-ug-
An electric dipole of moment is lying along a uniform electric field . The work done in rotating the dipole by 90 is :-
1
p E
2
pE
3
pE/2
4
2pE
Official Solution
Correct Option:
(1)
Work done in rotating a dipole from to is
Here therefore
24
PYQ 2007
easy
physicsID: neet-ug-
A hollow cylinder has a charge coulomb within it. If is the electric flux in units of voltmeter associated with the curved surface , the flux linked with the plane surface in units of voltmeter will be-
1
2
3
4
Official Solution
Correct Option:
(4)
25
PYQ 2007
easy
physicsID: neet-ug-
Two condensers, one of capacity and the other capacity are connected to a -volt battery, as shown in the figure. The work done in charging fully both the condensers is
1
2
3
4
Official Solution
Correct Option:
(2)
Work done in charging fully both the condensers, then
Therefore, the correct option is (B) :
26
PYQ 2007
medium
physicsID: neet-ug-
Charges and are placed at points and respectively which are a distance apart, is the midpoint between and . The work done in moving a charge along the semicircle is
1
2
3
4
Official Solution
Correct Option:
(3)
here
27
PYQ 2008
hard
physicsID: neet-ug-
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 is E, is
1
2
3
4
Official Solution
Correct Option:
(3)
Energy required =
28
PYQ 2008
easy
physicsID: neet-ug-
A thin conducting ring of radius R is given a charge + The electric field at the center O of the ring due to the charge on the part AKB of the ring is E. The electric field at the center due to the charge on the part ACDB of the ring is
Official Solution
Correct Option:
(1)
29
PYQ 2009
medium
physicsID: neet-ug-
The electric potential at a point is given by The electric field at that point is
1
2
3
4
Official Solution
Correct Option:
(4)
30
PYQ 2010
medium
physicsID: neet-ug-
A series combination of capacitors, each of value , is charged by a source of potential difference . When another parallel combination of capacitors, each of value , is charged by a source of potential difference , it has the same (total) energy stored in it, as the first combination has. The value of , in terms of , is then
1
2
16
3
2
4
Official Solution
Correct Option:
(4)
A series combination of , capacitors each of capacitance are connected to source as shown in the figure.
Total capacitance of the series combination of the capacitors is upto terms or ...(i) Total energy stored in a series combination of the capacitors is (Using (i)) ..... (ii) A parallel combination of capacitors each of capacitance are connected to V source as shown in the figure.
Total capacitance of the parallel combination of capacitors is upto trems or ...(iii) Total energy stored in a parallel combination of capacitors is
= (Using (iii))...(iv) According to the given problem,
Substituting the values of and from equations (ii) and (iv), we get
or or
31
PYQ 2011
medium
physicsID: neet-ug-
Four electric charges and are placed at the corners of a square of side (see figure). The electric potential at point , midway between the two charges and , is
1
2
3
4
zero
Official Solution
Correct Option:
(3)
32
PYQ 2011
medium
physicsID: neet-ug-
Three charges, each , are placed a at the corners of an isosceles triangle of sides and , . and are the mid points of and . The work done in taking a charge from to is
1
2
3
4
zero
Official Solution
Correct Option:
(4)
33
PYQ 2012
easy
physicsID: neet-ug-
A parallel plate capacitor has a uniform electric field E in the space between the plates. If the distance between the plates is d and area of each plate is A, the eneigy stored in the capacitor is
1
2
3
4
Official Solution
Correct Option:
(3)
Capacitance of a parallel plate capacitor is
Potential difference between the plates is
The energy stored in the capacitor is (Using (i) and (ii))
34
PYQ 2012
medium
physicsID: neet-ug-
What is the flux through a cube of side a if a point charge of q is at one of its corner?
1
2
3
4
Official Solution
Correct Option:
(2)
flux
35
PYQ 2014
medium
physicsID: neet-ug-
Two thin dielectric slabs of dielectric constants K1 and K2 (K1 < K2) are inserted between plates of a parallel plate capacitor, as shown in the figure. The variation of electric field 'E' between the plates with distance 'd' as measured from plate P is correctly shown by:
1
2
3
4
Official Solution
Correct Option:
(2)
The correct option (B):
36
PYQ 2014
easy
physicsID: neet-ug-
A conducting sphere of radius is given a charge . The electric potential and the electric field at the centre of the sphere respectively are
1
Zero and
2
and Zero
3
and
4
Both are Zero
Official Solution
Correct Option:
(2)
For the conducting sphere, Potential at the centre = Potential on the sphere
Electric field at the centre = 0
37
PYQ 2014
hard
physicsID: neet-ug-
In a region, the potential is represented by V(x, y, z) = 6x - 8xy - 8y + 6yz, where is in volts and are in metres. The electric force experienced by a charge of coulomb situated at point is
1
2
30 N
3
24 N
4
Official Solution
Correct Option:
(4)
Here, V(x, y, z) = 6x - 8xy - 8y + 6yz The x, y and z components of electric field are
At point (1, 1, 1)
The magnitude of electric field is
Electric force experienced by the charge
38
PYQ 2015
medium
physicsID: neet-ug-
A parallel plate air capacitor has capacity , distance of separation between plates is and potential difference is applied between the plates. Force of attraction between the plates of the parallel plate air capacitor is
1
2
3
4
Official Solution
Correct Option:
(4)
Force of attraction between the plates of the parallel plate air capacitor is
where Q is the charge on the capacitor, is the permittivity of free space and A is the area of each plate. But Q = CV and or
39
PYQ 2015
medium
physicsID: neet-ug-
A parallel plate air capacitor of capacitance C is connected to a cell of emf V and then disconnected from it. A dielectric slab of dielectric constant K, which can just fill the air gap of the capacitor, is now inserted in it. Which of the following is incorrect?
1
The change in energy stored is
2
The charge on the capacitor is not conserved
3
The potential difference between the plates decreases K times
4
The energy stored in the capacitor decreases K times
Official Solution
Correct Option:
(2)
Due to dielectric insertion, new capacitance Initial energy stored in capacitor, Final energy stored in capacitor, Change in energy stored,
New potential difference between plates
40
PYQ 2015
easy
physicsID: neet-ug-
If potential (in volts) in a region is expressed as = , the electric field at point is
1
2
3
4
Official Solution
Correct Option:
(4)
The electric field, and potential V in a region are related as
Here,
At point (1, 1,0),
41
PYQ 2015
medium
physicsID: neet-ug-
The enolic form of ethyl acetoacetate as below has
1
9 sigma bonds and 2 pi-bonds
2
9 sigma bonds and 1 pi-bond
3
18 sigma bonds and 2 pi-bonds
4
16 sigma bonds and 1 pi-bond
Official Solution
Correct Option:
(3)
bonds and bonds are present.
42
PYQ 2016
easy
physicsID: neet-ug-
A parallel-plate capacitor of area , plate separation d and capacitance is filled with four dielectric materials having dielectric constants and as shown in the figure below. If a single dielectric material is to be used to have the same capacitance in this capacitor, then its dielectric constant is given by
1
2
3
4
Official Solution
Correct Option:
(3)
Capacitance and Spring Constants Calculation
We are given the following equations and need to solve for the relationship between different parameters:
1. Capacitance Formula
The formula for the total capacitance of two capacitors in parallel is given by:
2. Rearranged Equation for Capacitor in Terms of Spring Constants
The equation involving spring constants and capacitance is:
3. Simplifying the Equation
Next, we simplify the equation by factoring out :
4. Final Simplified Expression
The final simplified form of the equation is:
Conclusion:
The equation shows the relationship between the spring constants and the overall constant . By solving for these constants, we can find the total system behavior in terms of its capacitance and spring constants.
43
PYQ 2017
medium
physicsID: neet-ug-
Suppose the charge of a proton and an electron differ slightly. One of them is –e, the other is (e +△e). If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then △e is of the order of [Given mass of hydrogen mh = 1.67 × 10–27 kg]
1
10–20 C
2
10–23 C
3
10–37 C
4
10–47 C
Official Solution
Correct Option:
(3)
The correct option is (C): 10–37 C.
44
PYQ 2017
medium
physicsID: neet-ug-
The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is
1
2
2
1
3
4
4
0.5
Official Solution
Correct Option:
(3)
The correct option is (C): 4.
45
PYQ 2017
easy
physicsID: neet-ug-
A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system :
1
Decreases by a factor of 2
2
Remains the same
3
Increases by a factor of 2
4
Increases by a factor of 4
Official Solution
Correct Option:
(1)
Charge on capacitor
when it is connected with another uncharged capacitor.
Initial energy
Final energy
Loss of energy
i.e. decreases by a factor (2)
46
PYQ 2017
medium
physicsID: neet-ug-
An arrangement of three parallel straight wires placed perpendicular to plane of paper carrying same current ‘I’ along the same direction is shown in Fig. Magnitude of force per unit length on the middle wire ‘B’ is given by
1
2
3
4
Official Solution
Correct Option:
(4)
The correct option is (D): .
47
PYQ 2018
medium
physicsID: neet-ug-
The electrostatic force between the metal plate of an isolated parallel plate capacitor having charge and area , is
1
inversely proportional to the distance between the plates.
2
independent of the distance between the plates.
3
proportional to the square root of the distance between the plates.
4
linearly proportional to the distance between the plates.
Official Solution
Correct Option:
(2)
For isolated capacitor Constant
is Independent of the distance between plates.
48
PYQ 2020
medium
physicsID: neet-ug-
The energy required to break one bond in DNA is . This value in eV is nearly
1
6
2
0.6
3
0.06
4
0.006
Official Solution
Correct Option:
(3)
Given: The energy required to break one bond in DNA is
We know:
So,
Substituting
Therefore, the energy required to break one bond in DNA is,
49
PYQ 2020
medium
physicsID: neet-ug-
In a certain region of space with volume , the electric potential is found to be throughout. The magnitude of electric field in this region is:
1
zero
2
0.5 N/C
3
1 N/C
4
5 N/C
Official Solution
Correct Option:
(1)
Since electric potential is found throughout constant, hence electric field,
50
PYQ 2020
medium
physicsID: neet-ug-
A short electric dipole has a dipole moment of . The electric potential due to the dipole at a point at a distance of from the centre of the dipole, situated on a line making an angle of with the dipole axis is :
1
2
3
4
zero
Official Solution
Correct Option:
(2)
The correct answer is B: The electric potential due to the dipole,
Here:
Putting these values in the formula we get;
51
PYQ 2021
easy
physicsID: neet-ug-
The total capacity of the system of capacitors shown in the adjoining figure between the points A and B is
1
1μF
2
2μF
3
3μF
4
4μF
Official Solution
Correct Option:
(2)
The problem involves finding the equivalent capacitance of the given system of capacitors between points A and B. Let's analyze the configuration step-by-step:
1. **Identify Series and Parallel Combinations**:
The two capacitors each of on the top and bottom are in parallel.
The capacitor in the middle is in series with the combination of the two capacitors.
2. **Calculate Equivalent Capacitance of Parallel Capacitors**:
The top two capacitors in parallel have an equivalent capacitance:
The bottom two capacitors in parallel also have an equivalent capacitance:
3. **Calculate Equivalent Capacitance of Series Combination**:
The capacitor in the middle is in series with the above configurations, and the from both sides is also connected, forming a combination:
4. **Final Series Combinations**:
To find the total capacitance between A and B, consider the two central capacitors are symmetrical around the common , effectively making it in parallel, yielding:
Therefore, the total capacitance is as the configurations were symmetrical.
5. **Conclusion**:
The total equivalent capacitance between A and B is:
Hence, the correct answer is 2μF.
52
PYQ 2021
medium
physicsID: neet-ug-
Twenty seven drops of same size are charged at 220 V each. They combine to form a bigger drop. Calculate the potential of the bigger drop
1
1980 V
2
660 V
3
1320 V
4
1520 V
Official Solution
Correct Option:
(1)
Let's solve the problem step-by-step to find the potential of the bigger drop formed by combining 27 identical drops, each charged at 220 V.
Step 1: Calculate the charge on one small drop
The potential of a drop is given by the formula:
where is Coulomb's constant, is the charge on the drop, and is the radius of the drop.
Rearranging, we find the charge on one drop:
Since all 27 drops are identical, each has the same charge .
Step 2: Combine the charges
When the drops combine to form a bigger drop, their total charge is the sum of the charges of the 27 smaller drops:
Step 3: Relate the volumes of the drops
Since volume is proportional to the cube of the radius, we have:
where is the radius of the bigger drop.
This implies:
Step 4: Calculate the potential of the bigger drop
The potential of the bigger drop is given by:
Substituting and :
Since each small drop has a potential of :
Thus, the potential of the bigger drop is 1980 V.
The correct answer is therefore .
53
PYQ 2021
easy
physicsID: neet-ug-
A parallel plate capacitor has a uniform electric field ‘ E → ’ in the space between the plates. If the distance between the plates is ‘d’ and the area of each plate is ‘A’, the energy stored in the capacitor is : (ε0=permittivity of free space)
1
2
3
4
Official Solution
Correct Option:
(4)
To find the energy stored in a parallel plate capacitor with a uniform electric field between the plates, we need to understand the relationship between the electric field, the charge, and the potential difference.
The relevant parameters given are:
The electric field .
The distance between the plates: .
The area of each plate: .
Permittivity of free space: .
Step 1: Understand the potential difference.
The potential difference between the plates is related to the electric field and the distance by:
Step 2: Calculate the charge on the capacitor.
The capacitance of a parallel plate capacitor is given by the formula:
Therefore, the charge on the capacitor can be related to the capacitance and potential difference by:
Step 3: Calculate the energy stored in the capacitor.
The energy stored in a capacitor is given by:
Substitute the expressions for and :
Thus, the energy stored in the capacitor is:
Conclusion:
The correct option for the energy stored in the capacitor is:
Hence, the correct answer is the fourth option: .
54
PYQ 2023
hard
physicsID: neet-ug-
An electric dipole is placed as shown in the figure. The electric potential (in 102 V) at point P due to the dipole is (ε0 = permittivity of free space and ):
1
2
3
4
Official Solution
Correct Option:
(4)
To find the electric potential at point P due to an electric dipole, we first need to understand the components involved:
An electric dipole consists of two charges, +q and -q, separated by a distance d.
Point P is located at distances r1 and r2 from the positive and negative charges, respectively.
The potential due to each charge is given by , where k is the Coulomb's constant .
The total potential at point P is the algebraic sum of the potentials due to each charge:
This can be rewritten as:
From the given diagram and problem context, it assumes specific values to compute:
Therefore, the potential
Multiplying and simplifying
Given that , potentially the distances and further calculations have finally resolved to match this solution identity:
The correct choice is: .
About Electrostatic Potential And Capacitance - NEET-UG
Electrostatic Potential And Capacitance is a vital chapter for NEET-UG aspirants. Mastering the concepts covered in this chapter is essential for securing a top rank.
By rigorously practicing the previous year questions associated with this chapter, you can identify high-yield topics, understand the examiner's perspective, and boost your confidence during the actual exam.
Frequently Asked Questions
Why focus on Electrostatic Potential And Capacitance PYQs?
Analyzing PYQs for this specific chapter reveals the most frequently tested concepts and the typical complexity of questions, allowing you to tailor your study plan efficiently.
How to best use this analysis?
Review the topic breakdown to see which sub-topics within Electrostatic Potential And Capacitance carry the most weight. Then, tackle the questions iteratively to solidify your understanding.
