The volume charge density of a sphere of radius 6 m is 2μC cm-3. The number of lines of force per unit surface area coming out from the surface of the sphere is _______ × 1010 NC-1.
Correct Answer: 45
Solution and Explanation
The number of lines of force per unit surface is nothing but an Electric field at that point
E=ρ\(\frac{r}{3}\)ϵ0, for r=R
E=ρ\(\frac{R}{3}\)ϵ0=2×\(\frac{6}{3}\)×8.85×10-12=0.45×1012 NC-1
=45×1010 N/C
Top Questions on Electrostatic potential
You are given a dipole of charge \( +q \) and \( -q \) separated by a distance \( 2l \). A sphere 'A' of radius \( R \) passes through the centre of the dipole as shown below and another sphere 'B' of radius \( 2R \) passes through the charge \( +q \). Then the electric flux through the sphere A is
- KCET - 2025
- Physics
- Electrostatic potential
- The electric field at a point in space is \( 2 \times 10^3 \, \text{N/C} \) and the potential at the same point is 100 V. What is the potential energy of a charge of 5 μC placed at that point?
- MHT CET - 2025
- Physics
- Electrostatic potential
- What is the energy stored in a capacitor of capacitance \( C = 10 \, \mu\text{F} \) when a potential difference of \( V = 20 \, \text{V} \) is applied across it?
- MHT CET - 2025
- Physics
- Electrostatic potential
Two charges, \( q_1 = +3 \, \mu C \) and \( q_2 = -4 \, \mu C \), are placed 20 cm apart. Calculate the force between the charges.
- MHT CET - 2025
- Physics
- Electrostatic potential
- Three-point charges \( Q \), \( q \), and \( -q \) are kept at the vertices of an equilateral triangle of side \( L \). What is the total electrostatic potential energy of the system?
- MHT CET - 2025
- Physics
- Electrostatic potential
Questions Asked in JEE Main exam
- The system of linear equations
$x + y + z = 6$
$2x + 5y + az = 36$
$x + 2y + 3z = b$
has- JEE Main - 2026
- Matrices and Determinants
- The displacement of a particle executing simple harmonic motion with time period \(T\) is expressed as \[ x(t)=A\sin\omega t, \] where \(A\) is the amplitude of oscillation. If the maximum value of the potential energy of the oscillator is found at \[ t=\frac{T}{2\beta}, \] then the value of \(\beta\) is ________.
- JEE Main - 2026
- Waves and Oscillations
- A complex number 'z' satisfy both \(|z-6|=5\) & \(|z+2-6i|=5\) simultaneously. Find the value of \(z^3 + 3z^2 - 15z + 141\).
- JEE Main - 2026
- Algebra
In the given figure, the blocks $A$, $B$ and $C$ weigh $4\,\text{kg}$, $6\,\text{kg}$ and $8\,\text{kg}$ respectively. The coefficient of sliding friction between any two surfaces is $0.5$. The force $\vec{F}$ required to slide the block $C$ with constant speed is ___ N.
(Given: $g = 10\,\text{m s}^{-2}$)
- JEE Main - 2026
- Rotational Mechanics
Two circular discs of radius \(10\) cm each are joined at their centres by a rod, as shown in the figure. The length of the rod is \(30\) cm and its mass is \(600\) g. The mass of each disc is also \(600\) g. If the applied torque between the two discs is \(43\times10^{-7}\) dyne·cm, then the angular acceleration of the system about the given axis \(AB\) is ________ rad s\(^{-2}\).
- JEE Main - 2026
- Rotational motion
Concepts Used:
Electrostatic Potential
The electrostatic potential is also known as the electric field potential, electric potential, or potential drop is defined as “The amount of work that is done in order to move a unit charge from a reference point to a specific point inside the field without producing an acceleration.”
SI Unit of Electrostatic Potential:
SI unit of electrostatic potential - volt
Other units - statvolt
Symbol of electrostatic potential - V or φ
Dimensional formula - ML2T3I-1
Electric Potential Formula:
The electric potential energy of the system is given by the following formula:
U = 1/(4πεº) × [q1q2/d]
Where q1 and q2 are the two charges that are separated by the distance d.