Ans. Electric Potential is the amount of work needed to move a unit charge from a reference point to a specific point against an electric field. The reference point is Earth, although any point that falls beyond the influence of the electric field charge can be used. Electric potential difference is the external work needed to bring a charge from one location to another location in an electric field.
In the International System of Units (SI), the electric potential is expressed in units of joules per coulomb (i.e., volts), and differences in potential energy are measured with a voltmeter.
Let us use positive charge q` to calculate the potential at point A that is distanced at r from a charge q.
Now, the force exerted by the test charge q` on the charge q placed at point A will be as such,
F= k(q.q`)/r2 …(1)
The electric field due to charge q at point A will be given as such, E= F/ q` (since the electric field is force per unit charge)
Placing the value of F from equation 1 we get,
E= {k(q.q`)/r2}/q`
or, E= kq/r2 ….(2)
Therefore, the value of the electric potential at point A can be given as,
V= E*r …..(3)
Now, by placing the value of E from equation 2 in equation 3 we get,
V=( kq/r2)*r
thus, V= kq/r ….(4)
Let a test charge q is being moved from point R to point P against the repulsive force of charge Q.
Therefore, to bring charge q from point R to P the force required can be taken as Fext = -FE (negative because the same is a repulsive force)
Or, work done,
Or, WRP = ∫ PR Fext. dr = -∫ PR FE. dr
The above expression explains that the work done will be stored in the form of potential energy. When the external force is thus removed, the charge q moves further from Q as a result of the repulsive force. The potential energy gets converted into kinetic energy and thus the sum remains reserved.
Find work done in bringing charge q = 3nC from infinity to point A as shown in the figure : 
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Time period of a simple pendulum is longer at the top of a mountain than that at the base of the mountain.
Reason (R): Time period of a simple pendulum decreases with increasing value of acceleration due to gravity and vice-versa. In the light of the above statements, choose the most appropriate answer from the options given below:
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Choke coil is simply a coil having a large inductance but a small resistance. Choke coils are used with fluorescent mercury-tube fittings. If household electric power is directly connected to a mercury tube, the tube will be damaged.
Reason (R): By using the choke coil, the voltage across the tube is reduced by a factor \( \frac{R}{\sqrt{R^2 + \omega^2 L^2}} \), where \( \omega \) is the frequency of the supply across resistor \( R \) and inductor \( L \). If the choke coil were not used, the voltage across the resistor would be the same as the applied voltage.
In light of the above statements, choose the most appropriate answer from the options given below:
The potential of a point is defined as the work done per unit charge that results in bringing a charge from infinity to a certain point.
Some major things that we should know about electric potential:
The ability of a capacitor of holding the energy in form of an electric charge is defined as capacitance. Similarly, we can also say that capacitance is the storing ability of capacitors, and the unit in which they are measured is “farads”.
Read More: Electrostatic Potential and Capacitance
Both the Capacitors C1 and C2 can easily get connected in series. When the capacitors are connected in series then the total capacitance that is Ctotal is less than any one of the capacitor’s capacitance.
Both Capacitor C1 and C2 are connected in parallel. When the capacitors are connected parallelly then the total capacitance that is Ctotal is any one of the capacitor’s capacitance.