Electricity Formulas

Electricity Formula

Electricity is the flow of charge in a conductor from anode to cathode. Electricity has several applications. It functions as a power source for electrical gadgets. We can say that charge flow generates a current, or electricity. To comprehend how electricity is generated, we must first grasp the basic factors related with it, such as voltage, current, resistance, and conductivity, as well as their relationships. Electricity formula helps us to quantify the terms related to the electricity. In this article, we will study formulas related to electricity and solve examples based on them

What is Electricity?

Electricity is the flow of electrons from one atom to another in a medium or through vacuum. Every atom consists of three fundamental components: electrons, protons, and neutrons.

When the attraction between protons and electrons is not strong enough in an atom to hold electrons in their orbits, electrons can be freed from their orbits by an external force and move to nearby atoms.

This shift causes an imbalance, which is called ‘charge’ and the flow of charge is called simply electric current.

Electricity is a form of energy. It can be harnessed in various ways, like converting primary sources of energy such as coal, natural gas, nuclear energy, solar energy, and wind energy into electrical energy or through chemical reactions as in batteries.

The basic units of measurement for electricity are current (I), voltage (V), and resistance (R).

Current (I): Current is the rate of flow of charge through a conductor. It is measured in amperes, or amps (A).

Voltage (V): Voltage is the difference in the concentration of electrons between two points. This is measured in volts.

Resistance (R): Resistance is the measure of obstruction to the flow of charge in a conductor. It is calculated by the material length, cross-sectional area, and temperature of the material. It is measured in ohms (Ω).

Power (P):  Power is the rate of energy consumed or transferred by an electric circuit. It is measured in watts (W).

What are Electricity Formulas?

Electricity formulas consist of all the formulas of the terms associated with electricity

Current (I) Formula

Current is given as ratio of charge and time

I= Q/t


  • I represents current (measured in amperes, A),
  • Q represents electric charge (measured in coulombs, C)
  • t represents time (measured in seconds, s)

Voltage(V) Formula

Voltage is calculated by finding work done per unit charge

V= W/Q


  • V represents voltage (measured in volts, V)
  • W represents work done (measured in joules, J)
  • Q represents electric charge (measured in coulombs, C)

Resistance (R) Formula

Resistance is found using Ohm’s law which is given as V = IR

R = V / I

  • R represents resistance (measured in ohms, Ω)
  • V represents voltage (measured in volts, V)
  • I represents current (measured in amperes, A)

Power (P) Formula

Power is rate of work done by electric charge. It can be calculated using any of the three formulas mentioned below

  • P= V x I
  • P = I2 x R
  • P = V² / R


  • P represents power (measured in watts, W)
  • V represents voltage (measured in volts, V)
  • I represents current (measured in amperes, A)
  • R represents resistance (measured in ohms, Ω)

Electricity Formula Chart

The Electricity formulas are the physical occurrence of the presence and movement of electric charge. To understand how electricity is created, electrons are loosely packed by the nucleus and travel freely inside the body. Because they are negatively charged particles, when they produce multiple charges, the movement is known as electric current or electricity.

Quantity Formulas Unit
Current I I = Q / t

  • Q = Charge
  • t = time taken
Amperes (A)
Voltage V V = E / Q


V = W / Q

  • E = Energy,
  • W = Work done
Volts (V)
Resistance R R = ρl / A

  • ρ = Resistivity,
  • l = length,
  • A = Area


R = V / I

Ohm (Ω)
Power P P = VI Watts (W)
Conductivity σ = 1 / ρ Siemens per meter (S/m)

Electricity and its Effect (notations)

Physical Quantity Symbols SI unit
Voltage (potential difference) V Volt(V)
Power P Watt(W)
Charge Q Coulomb (C)
Work or Energy W Joule (J)
Resistance R Ohm Ω
Current I Ampere (A)
Resistivity ρ Ohm metre (Ω m)

Solved Examples

Example 1 : An electric heater has a potential difference of 220 V and a resistance of 11 Ω. Determine the magnitude of the current that passes through it.



Resistance R = 11 Ω

Voltage V = 220 V

The current formula is given by

I = V / R

= 220 / 11

I = 20 A

Example 2 : An electrical lamp lights for 6 hours and draws a current of 0.3 A. Find the amount of charge flowing through the lamp.


Current I = 0.3 A

Time taken t = 6 hours

t= 6 × 3600 = 21600 s,

Charge Q = I × t

= 0.3 ×21600

Q= 6480 C

Example 3: A circuit has a resistance of 10 ohms (Ω) and is connected to a voltage source of 20 volts (V). Calculate the current flowing through the circuit.


Ohm’s Law states that the current I flowing through a circuit is directly proportional to the voltage V and inversely proportional to the resistance R. The formula is given by I = V/R

  • Voltage,
  • Resistance,
    R = 10 \text{ Ω}

Hence, I = 20/10 = 2 A

Physics Related Formulas
Electric Field Formula Poynting Vector Formula
Gross Profit Formula Refraction Formula
Mass Formula Sound Intensity Formula
Capacitance Formula Uniform Circular Motion Formula
Centripetal Force Formula Thermal Expansion Formula
Distance Speed Time Formula Thermal Energy Formula
Ohms Law Formula Amperes Law Formula
Refractive Index Formula Horsepower Formula
Wavelength Formula Lattice Energy Formula
Stress Formula Length Contraction Formula

FAQs (Frequently Asked Questions)

1. What is the formula for calculating current?

The formula for calculating current is I = Q / t

where I is current, Q is charge, and t is time taken.

2. What is the formula for resistance?

The formula for resistance is –

R = ρl / A or R = V / I

where R is resistance, ρ is resistivity, l is length, A is area, V is voltage, and I is current.

3. How is voltage calculated?

Voltage can be calculated using the formula

V = E / Q or V = W / Q

where V is voltage, E is energy, W is work done, and Q is charge.

4. What is Ohm's Law?

Ohm’s Law states that voltage equals current multiplied by resistance:

V= I × R

5. How is electricity generated?

Electricity can be generated using various methods including burning fossil fuels, nuclear reactions, and harnessing renewable energy sources like solar, wind, and hydro power.