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MCQ (Single Correct Answer)

1
A bob of a simple pendulum has a mass of 4 g and a charge of $20 \mu \mathrm{C}$. If it is at rest in a uniform horizontal electric field of intensity $1000 \mathrm{Vm}^{-1}$, the angle that the pendulum makes with the vertical at equilibrium is:
COMEDK 2025 Evening Shift
2

Three charges, $Q,-q$ and $2 q$ are placed at the vertices of a right-angled isosceles triangle. What is the value of $q$ for the net electrostatic energy of the configuration to be zero?

COMEDK 2025 Evening Shift Physics - Electrostatics Question 1 English

COMEDK 2025 Evening Shift
3
A particle of mass 3 g and charge $60 \mu \mathrm{C}$ is released from rest in a uniform electric field of intensity $10^5 N C^{-1}$. If the value of kinetic energy attained by the particle after moving through a distance of 2 cm is $m \times 10^{-2} J$, then the value of m is:
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4
A uniformly charged conducting sphere of 0.2 m diameter has a surface charge density of $70 \mu \mathrm{Cm}^{-2}$. The electric flux leaving the surface of the sphere is:
COMEDK 2025 Evening Shift
5
Two electric dipoles of dipole moments $3.9 \times 10^{-30} \mathrm{Cm}$ and $5.2 \times 10^{-30} \mathrm{Cm}$ are placed in two different uniform electric fields of strengths $16 \times 10^4 \mathrm{NC}^{-1}$ and $4 \times 10^4 \mathrm{NC}^{-1}$ respectively. What is the ratio of maximum torque experienced by the electric dipoles?
COMEDK 2025 Evening Shift
6
A particle ' X ' carrying a charge +Q is moving in a circular path of radius R around another particle ' Y ' having a charge -Q with a frequency ' $v$ '. Then the mass ' $m$ ' of the charged particle is
COMEDK 2025 Afternoon Shift
7
Three point charges $-1 C,+1 C,+1 C$ are placed at points $A, B, C$ respectively of a triangle $A B C$. What is the total potential energy of the system? [given $\mathrm{AB}=\mathrm{AC}=6 \mathrm{~cm}$ and $\mathrm{BC}=3 \mathrm{~cm}$ ]
COMEDK 2025 Afternoon Shift
8

The electric field versus distance graph is shown as given. Select the correct statement from the following.

E- electric field

R-radius

r - distance from the centre

COMEDK 2025 Afternoon Shift Physics - Electrostatics Question 6 English

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9
What is the dimensional formula for electric flux?
COMEDK 2025 Afternoon Shift
10
When a metallic spherical shell of radius 20 cm is charged, the potential on its surface is found to be 5 V . The potential at a point 10 cm from the centre of the spherical shell is :
COMEDK 2025 Afternoon Shift
11
Point charges $-3 Q,-q, 2 q$ and $2 Q$ are placed, one at each corner of a square. The relation between Q and q for which the potential at the centre of the square is zero is
COMEDK 2025 Morning Shift
12

For the charge configuration shown here, which of the following is not true?

COMEDK 2025 Morning Shift Physics - Electrostatics Question 11 English

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13
Two identical conducting balls having positive charges $q_1$ and $q_2$ are separated by a distance $r$. If they are made to touch each other and then separated to the same distance, the force between them will be
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14

A neutral water molecule is placed in an electric field $$E=2.5 \times 10^4 \mathrm{NC}^{-1}$$. The work done to rotate it by $$180^{\circ}$$ is $$5 \times 10^{-25} \mathrm{~J}$$. Find the approximate separation of centre of charges.

COMEDK 2024 Evening Shift
15

Two point charges $$\mathrm{M}$$ and $$\mathrm{N}$$ having charges $$+q$$ and $$-q$$ respectively are placed at a distance apart. Force acting between them is $$\mathrm{F}$$. If $$30 \%$$ of charge of $$\mathrm{N}$$ is transferred to $$\mathrm{M}$$, then the force between the charges becomes:

COMEDK 2024 Evening Shift
16

If 216 drops of the same size are charged at $$200 \mathrm{~V}$$ each and they combine to form a bigger drop, the potential of the bigger drop will be

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17

Three point charges are located on a circular arc at $$\mathrm{A}, \mathrm{B}$$ and $$\mathrm{C}$$ as shown in the figure below. The total electric field at the centre of the $$\operatorname{arc}(\mathrm{C})$$ is

COMEDK 2024 Evening Shift Physics - Electrostatics Question 14 English

COMEDK 2024 Evening Shift
18

A tiny ball of mass $$\mathrm{m}$$ and charge $$\mathrm{q}$$ is suspended from the fixed support using an insulating string of length $$1 \mathrm{~m}$$. The horizontal uniform electric field $$\mathrm{E}$$ is switched on. The angle made by the string with vertical when the ball is in equilibrium is $$45^{\circ}$$. The magnitude of uniform electric field is

COMEDK 2024 Afternoon Shift
19

Figure shows three arrangements of electric field lines. In each arrangement, a proton is released from rest at point $$\mathrm{P}$$ and then accelerated through point $$\mathrm{Q}$$ by the electric field. Points $$\mathrm{P}$$ and $$\mathrm{Q}$$ have equal separations in the three arrangements. If $$p_1 p_2$$ and $$p_3$$ are linear momentum of the proton at point $$\mathrm{Q}$$ in the three arrangement respectively, then

COMEDK 2024 Afternoon Shift
20

3 point charges each of $$-\mathrm{q}$$ are placed on the circumference of a circle of diameter $$2 \mathrm{a}$$ at $$\mathrm{A}, \mathrm{B}$$ and $$\mathrm{C}$$ respectively as shown in figure. The electric field at $$\mathrm{O}$$ is

COMEDK 2024 Afternoon Shift Physics - Electrostatics Question 18 English

COMEDK 2024 Afternoon Shift
21

A uniformly charged solid sphere of radius $$\mathrm{R}$$ has potential $$\mathrm{V}_0$$ (measured with respect to infinity) on its surface. For this sphere the equipotential surfaces with potentials $$\frac{3 \mathrm{~V}_0}{2}, \frac{\mathrm{V}_0}{1}, \frac{3 \mathrm{~V}_0}{4}$$ and $$\frac{\mathrm{V}_0}{4}$$ have radius $$\mathrm{R}_1, \mathrm{R}_2, \mathrm{R}_3$$ and $$\mathrm{R}_4$$ and respectively, then

COMEDK 2024 Afternoon Shift
22

A square shaped aluminium coin weighs $$0.75 \mathrm{~g}$$ and its diagonal measures $$14 \mathrm{~mm}$$. It has equal amounts of positive and negative charges. Suppose those equal charges were concentrated in two charges $$(+Q$$ and $$-Q)$$ that are separated by a distance equal to the side of the coin, the dipole moment of the dipole is

COMEDK 2024 Morning Shift
23

If potential (in volt) in a region is expressed as $$\mathrm{V}(\mathrm{x}, \mathrm{y}, \mathrm{z})=6 \mathrm{xy}-\mathrm{y}+2 \mathrm{yz}$$, the electric field (in $$N C^{-1}$$) at point $$(1,0,1)$$ is

COMEDK 2024 Morning Shift
24

Five charges, '$$q$$' each are placed at the comers of a regular pentagon of side '$$a$$' as shown in figure. First, charge from '$$A$$' is removed with other charges intact, then charge at '$$A$$' is replaced with an equal opposite charge. The ratio of magnitudes of electric fields at $$\mathrm{O}$$, without charge at $$A$$ and that with equal and opposite charge at $$A$$ is

COMEDK 2024 Morning Shift Physics - Electrostatics Question 22 English

COMEDK 2024 Morning Shift
25

Two charges '$$-q$$' each are fixed, separated by distance '$$2 d$$'. A third charge '$$q$$' of mass '$$m$$' placed at the mid-point is displaced slightly by '$$x$$' $$(x< < d)$$ perpendicular to the line joining the two fixed charges as shown in Fig. The time period of oscillation of '$$q$$' will be

COMEDK 2024 Morning Shift Physics - Electrostatics Question 23 English

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26

Two metal spheres, one of radius $$\frac{R}{2}$$ and the other of radius $$2 \mathrm{R}$$ respectively have the same surface charge density They are brought in contact and separated. The ratio of their new surface charge densities is

COMEDK 2024 Morning Shift
27

When $$10^{19}$$ electrons are removed from a neutral metal plate, the electric charge on it is

COMEDK 2023 Morning Shift
28

Two point charges $$20 \mu \mathrm{C}$$ and $$-10 \mu \mathrm{C}$$ are separated by a distance of $$1 \mathrm{~m}$$ in air. At what point on the line joining the two charges, the electric potential is zero.

COMEDK 2023 Evening Shift
29

A spherical metal ball of density '$$\rho$$' and radius '$$r$$' is immersed in a liquid of density '$$\sigma$$'. When an electric field is applied in the upward direction the metal ball remains just suspended in the liquid. Then the expression for the charge on the metal ball is :

COMEDK 2023 Evening Shift
30

PQRS is square of side $$1 \mathrm{~m}$$. A charge of $$100 \mu \mathrm{C}$$ is placed at the centre of the square. Then the work done to take $$3 \mu \mathrm{C}$$ charge from the corner $$\mathrm{P}$$ to the corner $$\mathrm{R}$$.

COMEDK 2023 Evening Shift
31

An electron and a proton having mass $$m_e$$ and $$m_p$$ respectively, initially at rest, move through the same distance '$$s$$' in a uniform electric field '$$E$$'. If the time taken by them to cover that distance is $$t_e$$ and $$t_p$$ respectively, then $$t_e / t_p$$ is equal to:

COMEDK 2023 Evening Shift
32

The force between two electric point charges at rest in air is $$F_1$$ When the same arrangement is kept inside water, the force between them is $$F_2$$. Which of the following statement is correct?

COMEDK 2023 Evening Shift
33

Which of the following diagram represents the variation of the electric field with distance r from the centre of a uniformly charged non-conducting sphere of radius R?

COMEDK 2022
34

Charge on electron is

COMEDK 2022
35

Two charged spheres of $$-20\mu$$C and $$60\mu$$C are kept at a certain distance. They are touched and kept again at the same distance. What is the ratio of force experienced before and after?

COMEDK 2022
36

Insulators can be charged by which of the following process?

COMEDK 2021
37

Work done in moving a charge of 25C is 50 J. Calculate potential difference, between two points.

COMEDK 2021
38

What is the electric field near infinite plane sheet of charge density $$\sigma$$ ?

COMEDK 2021
39

Consider a thin spherical shell of radius R consisting of uniform surface charge density s. The electric field at a point of distance x from its centre and outside the shell is

COMEDK 2020
40

A charge of 0.8 C is divided into two charges Q$$_1$$ and Q$$_2$$. These are kept at a separation of 30 cm. The force on Q$$_1$$ is maximum when

COMEDK 2020
41

An electric dipole has a pair of equal and opposite point charges $$q$$ and $$-q$$ separated by a distance $$2x$$. The axis of the dipole is defined as

COMEDK 2020
42

An electric dipole is placed in a uniform electric field with the dipole axis making an angle $$\theta$$ with the direction of the electric field. The orientation of the dipole for stable equilibrium is

COMEDK 2020
43

Two point charges A = +3 nC and B = +1 nC are placed 5 cm apart in air. The work done to move charge B towards A by 1 cm is

COMEDK 2020
44

The potential energies associated with four orientations of an electric dipole in an electric field are

(i) $$-5U_0$$ (ii) $$-7U_0$$ (iii) $$3U_0$$ (iv) $$5U_0$$

where $$U_0$$ is positive. Rank the orientations according to the angle between the electric dipole moment p and electric field E, greatest first

COMEDK 2020
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