Ultimate Guide to Electric Power Formula & Examples

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Ultimate Guide to Electric Power Formula & Examples
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Electric power is the measure of energy used over a given time. It is the rate at which electrical energy flows in a circuit. The power formula for electricity considers power in watts, current in amperes, and voltage in volts. In this article, we will delve into the basics of electric power, how to calculate the cost of electricity, and how to save electricity.

The Jackery Solar Generators are ideal and safe power solutions that could initiate your journey to electricity generation anytime. You will, therefore, consume less from the grid, which reduces the high electricity bills.

What Is Electric Power?

Power represents the rate at which energy is consumed or converted. In particular, electric power measures how often electric energy is turned into other forms, such as heat, light, or mechanical ones. The power-electricity formula is given as P = V * I. Here, P stands for the power measured in watts (W), V stands for voltage measured in volts (V), and I stands for current measured in amperes (A).

Ordinary life depends on electric power to perform certain tasks, including illuminating a bulb, running a motor, or charging a smartphone. In addition, it is used in transportation, global communications networks, and lighting systems. Power is important because it enables us to enjoy convenience, comfort, and safety in different aspects of our lives.

Electric current refers to the movement of subatomic charged particles like electrons, protons, ions, and holes with electron deficiency. Charge carriers are the electrons hence electric current being the amount of charge that passes through the wire for some time.

The phenomenon associated with electrical charges in motion is termed electricity. In this case, therefore, an electron has a negative charge. Various forms of electricity result from the cumulative motion of electrons.

Electric charge is defined as a fundamental property of matter carried by subatomic particles that determine how these particles are affected by an electric field. The electric charge occurs in many particles that make up matter.

Electric Energy: The Volt, The Amp, The Watt

P is an electric power in a circuit, the rate at which energy is generated or used. The power comes from an energy source, such as voltage, and is absorbed by the connected load. For instance, heaters and light bulbs use electricity to absorb their power into either light or heat, sometimes both. They are expected to draw more electricity if their wattage value is higher. A watt is the SI power unit, and it’s a scalar quantity.

Volts are units of electrical potential that measure electrical potential when electricity flows through a system. When one watt of power is dissipated between two points on a conductor carrying one ampere of current, the potential difference or voltage between those points equals one volt (V). A mathematical expression for voltages takes this form:

V = I * R where V refers to voltage in volts, I is current in amperes, and R stands for resistance in ohms.

Voltage unit can be expressed as the potential difference across any two points in an electric circuit that transfers one joule (J) of energy per coulomb (C) charge passing through.

1 Volt= 1 Joule / 1 Coulomb = J / C

Example: Let’s say you have a bulb of 60 watts. It operates with a voltage of 120 volts. This means the light bulb consumes electric power at the rate of 60 watts and 120 volts is the electric potential difference required for the current to flow.

The amount of current generated by one volt applied through one ohm of resistance is known as an ampere. A single coulomb of electrical charge is represented by one ampere of current. It is the same as one coulomb of charge per second.

1 Ampere = 1 Coulomb/ 1 Second

Example: Let’s consider a simple circuit with a light bulb of 80 watts operating at a voltage of 160 volts. If the resistance of the light bulb is 4 ohms, you can calculate the current as :

I= V / R= 160 / 4 = 40 A

The rate at which energy is converted into an electrical circuit or work is known as electric power. The electrical power unit known as a watt is one ampere at one volt of pressure. One watt is equivalent to 1 joule of energy transferred per second.

Example: Let’s consider a circuit in which a battery of 12 volts is connected to a light bulb. Let’s say the bulb has a resistance of 4 ohms. The current will be:

I = V / R = 12 V / 4 Ω = 3 A

So, the power will be :

P = V * I = 12 V × 3 A = 36 W.

Ohm’s Law VS. Joule’s Law

Ohm's law typically describes the relationship between three units: current, voltage, and resistance. The potential difference, or voltage, across a wide range of materials directly correlates with the amount of steady current flowing through them. It states that the current flowing is directly proportional to the potential difference across the two ends of the conductor. In that case, the physical conditions of the conductor should remain constant.

Ohm’s law is expressed as V ∝ I, where V is known as the potential difference, and I is the current.

The mathematical relationship is shown graphically by Ohm's Law triangle. I is the quotient of V and R, R is the quotient of V and I, and V is the product of I and R.

ohm law triangle with formulas

The formula for Ohm’s law can be expressed in three different ways:

V = I * R
I = V / R
R = V / I
Where V is voltage, I is current, and R is resistance.

ohms law wheel

Example: Consider you have a circuit with a resistance of 10 Ω and a current of 2 A. Using the formula V = IR, we get the voltage as V = 2 A × 10 Ω = 20 V

ohms law formulas

The wire's collision-producing electrons are what causes the heat. The rate at which resistance in a circuit transforms electrical energy into thermal energy is known as Joule's law. It illustrates the connection between the heat generated by any electric current that passes through a conductor.

It is denoted as : H = I2 * R * T.

H is the amount of heat, I is current, R denotes resistance, and T denotes time.

Example: Let's say that in an electric circuit, 5 amperes of current passes through a resistor of 10 ohms for 2 minutes. 
Using the formula, the heat produced will be :

H = I2 * R * T

H = 25 × 10 × 120
H = 60000 A2 Ω s

H = 60000 J

Most substances have a current that is directly proportional to the voltage V that is applied to it. A 1-ohm resistor will dissipate 1 joule of energy in 1 second with a current of 1 ampere and a potential difference of 1 volt. Ohm's Law and Joule's Law provide insight into the relationship between four units: voltage, current, resistance, and power. Both are essential components of electrical projects, and they help illustrate the electrical concepts surrounding transformers.

How is Electric Power Measured?

A wattmeter is an instrument for measuring the active electric power of a circuit. Utility frequency and audio frequency power are measured using electromagnetic wattmeters; radio frequency measurements require other kinds. Wattmeters are essential for researching harmonics, voltage variations, and energy-related power-related issues.

In a conventional electrodynamic wattmeter, the potential coil and the circuit are connected in parallel, while the current coils are connected in series. The current passing through the current coil creates an electromagnetic field surrounding it. This field's strength is in phase and proportionate to the line current. A digital wattmeter takes thousands of samples of voltage and current per second. The real power is the average over a minimum of one cycle, obtained by multiplying the voltage and current simultaneously for each sample.

How to Calculate The Cost of Electricity?   

To calculate the electricity cost, you must know your power consumption and habits that factor into your bills. By knowing the value of power consumption, energy price, and usage time, you can calculate the electricity cost using a calculator as well. There are also other methods, such as calculating your monthly bills manually and using a monitoring device.

Let's consider an example of how to calculate the electricity bill manually.

Let’s say you have an appliance that consumes 10 amperes of electricity at 120 volts, and you use this device for 50 hours at an electricity rate of $0.15 per kWh.

Using the formula : Watts = Amps × Volts

We get watts = 10 × 120 = 1200 watts

Now calculate the kilowatt-hours

kWh = (Watts × Time consumed) / 1000

kWh = (1200 × 50) / 1000 = 60 kWh- Hours

To calculate cost,

Cost = kWh × Electricity rate

Cost = 60 × $0.15 = $9

Energy is the ability to do work while existing in various forms such as potential, kinetic, chemical, or thermal. Power is the rate at which energy is converted per unit of time, and the amount and rate of energy transferred are often expressed over time.

Energy = Power × Time

The degree to which something achieves its outcome relative to the cost is referred to as cost-effectiveness. Some examples that can illustrate cost-effectiveness include energy-efficient appliances, home insulation, and education.

Improving the energy efficiency of homes, industries, and schools, which consume much of the energy in the United States, can achieve cost-effectiveness. This also helps to address the challenges of high energy prices and climate change. Linking energy efficiency with reduced consumption can eventually lower prices.

Here are some tips for saving electricity costs :

Monitor Compressed Air Systems

Fixing leaks can help you realize significant immediate savings, as they can be a major source of unused energy. According to reports, leaks can cause a compressor's output to drop by 20 to 30 percent. They may also make your equipment less effective. There are several methods, such as conducting an air leak survey, to determine if your system has leaks. Ultrasonic detection equipment is also available for smaller leaks.

Upgrade Your Appliances

Maintaining the functionality of your equipment is essential to increasing its energy efficiency. In the long run, though, the savings from replacing outdated machinery with computers, motors, and ceiling fans might add up. Make time in your schedule to inspect and maintain your equipment, not just the essentials.

Invest in Jackery Solar Generators

The Jackery Solar Generator combines a portable power station with solar panels. It emits no toxic gas and operates cleanly, causing no environmental harm. They offer a reliable green energy solution for home backup, reducing electricity consumption and costs.

Jackery Solar Generators for Saving Your Electricity

Jackery is a global brand that specializes in manufacturing portable power stations, solar generators, and portable solar panels. These are not only made for outdoor adventures but offer a sustainable and eco-friendly solution for charging indoor appliances, serving as an emergency backup, and saving power.

When the sunlight falls on the Jackery SolarSaga Solar Panels, they convert the sun's rays into DC electricity. This is then passed through the pure sine wave inverter of the Jackery Explorer Portable Power Station to produce usable AC electricity for charging appliances.

Jackery Explorer Portable Power Station harnesses energy from solar panels, providing convenient backup power during power outages. It is equipped with multiple outlets and can charge various devices simultaneously. Thus, you can operate devices without connecting to the grid, saving electricity costs.

Jackery Explorer 3000 Pro Portable Power Station

The Jackery Explorer 3000 Pro Portable Power Station can power up to 99% of outdoor and indoor appliances for a long time, which is ideal for home backup and emergencies, saving electricity and cost. It has a large battery capacity that can power most types of devices, such as refrigerators, TVs, lights, electric grills, and heaters.

jackery explorer 3000 pro portable power station for electric power supply


Explorer 3000 Pro Portable Power Station


3024 Wh

Battery Cell


Cycle Life

2000 cycles to 70%+ capacity

Recharging Methods

Solar Recharging : 3.5 H (6*Jackery SolarSaga 200W Solar Panels)

Wall Recharging : 2.5 H

Car Recharging : 35 H

Output Ports

AC Output (x1) : 120 V~ 60 Hz 25 A Max

AC Output (x3) : 120 V~ 60 Hz 20 A Max

USB-C Output (x2) : 100 W Max, 5 V⎓3 A, 9 V⎓3 A, 12 V⎓3 A, 15 V⎓3 A, 20 V⎓5 A

Car Port (x1) : 12 V, 10 A Max

Working Hours

Refrigerator (520 W) : 5 H
TV (60 W) : 43 H
Mobile phone (29 W) : 88.6 H
Heater (1800 W) : 1.4 H

Customer Review

“ I bought this generator for emergency use. I was surprised at how quickly it charged from the wall socket. Also, as the charge reaches full, the charging voltage drops.” — Ms Wilma.

Jackery Explorer 2000 Plus Portable Power Station

With a leaping performance of powering heavy-duty devices up to 6000W, the Jackery Explorer 2000 Plus Portable Power Station comes with a high power output. This is ideal for off-grid living and powering home appliances during extended blackouts. It just takes 2 hours for a full solar charge with the 6*Jackery SolarSaga 200W Solar Panels, and reduces the power consumption from grids.

jackery explorer 2000 plus portable power station for electric power supply


Explorer 2000 Plus Portable Power Station


2 - 24 kWh

Battery Cell

LFP (LiFePO4 battery)

Cycle Life

4000 cycles to 70%+ capacity

Recharging Methods

Solar Recharging : 2 H (6*Jackery SolarSaga 200W Solar Panels)

Wall Recharging : 2 H

Car Recharging : 25 H

Output Ports

AC Output (×4) :120 V~ 60 Hz, 20 A Max

AC Output (×1) :120 V~ 60 Hz, 25 A Max, AC Total Output,3000 W Max, 6000 W surge peak

USB-A Output (x2) : Quick Charge 3.0, 18 W Max

USB-C Output (x2) : 100 W Max, (5 V, 9 V, 12 V, 15 V, 20 V up to 5 A)

Car Port (x1) : 12 V⎓10 A

Working Hours

Portable Air Conditioner (1000 W) : 1.7 H
Electric Pressure Cooker (1080 W) : 1.6 H
Electric Oven (800 W) : 2.1 H
Outdoor Electric Grill (1700 W) : 1.02 H

Customer Review

“ I like this thing. It's got a lot of power. It powered my air conditioner on high. It powered power tools.” — Michael Wheeler.

Jackery Explorer 2000 Pro Portable Power Station

The Jackery Explorer 2000 Pro Portable Power Station comes with three ways to recharge. It can be used weekly for more than ten years and can power up to 8 devices at a time. It can satisfy the demand for electricity during outages. It can power a full-sized refrigerator, air conditioner, and hot plates.

jackery explorer 2000 pro portable power station for electric power supply

Explorer 2000 Pro Portable Power Station


2160 Wh

Battery Cell


Cycle Life

1000 cycles to 80%+ capacity

Recharging Methods

Solar Recharging : 2.5 H (6*Jackery SolarSaga 200W Solar Panels)

Wall Recharging : 1.7 H

Car Recharging : 7 H

Output Ports

AC Output(x3) : 120 V, 60 Hz, 2,200 W (4,400 W Peak)

USB-A Output(x2) : Quick Charge 3.0, 18 W Max

USB-C Output(x2) : 100 W Max, (5 V, 9 V, 12 V, 15 V, 20 V up to 5 A)

Car Port(x1) : 12 V⎓10 A

AC Input: 120 V, 60 Hz, 15 A Max

DC Input: 11 V-17.5 V, 8 A Max, Double to 8 A Max 17.5 V⎓60 V, 12 A, Double to 24 A/1400 W Max

Working Hours

Microwave (700 W) : 2.6 H
Kettle (850 W) : 2.1 H
Electric Drill (900 W) : 2.04
Electric Pressure Cooker (1080 W) : 1.7 H

Customer Review

“ Easy to charge. Perfect for our condo, where we cannot have an outdoor generator. Will let us have heat in the bedroom and run a CPAP machine.” — Audrey Bell.

Jackery Explorer 1000 Plus Portable Power Station

With a capacity of 1264 Wh, the Jackery Explorer 1000 Plus Portable Power Station supports 99% of devices. It provides support for home emergencies due to its versatility and expandable capacity. It can charge devices such as coffee makers, electric cookers, refrigerators, televisions, and many more.

jackery explorer 1000 plus portable power station for electric power supply


Explorer 1000 Plus Portable Power Station


1.2 - 5 kWh

Battery Cell


Cycle Life

4000 Cycles to 70%+ capacity

Recharging Methods

Solar Recharging : 2 H (6*Jackery SolarSaga 200W Solar Panels)

Wall Recharging : 1.7 H

Car Recharging : 7 H

Output Ports

AC Output(x3) : 120 V~60 Hz, 2000 W (4000 W Peak)

USB-A Output(x2) : 18 W Max, 5-5 V⎓3 A

USB-C Output(x2) : 100 W Max, (5 V, 9 V, 12 V, 15 V, 20 V up to 5 A)

Car Port(x1) : 12 V⎓10 A

Working Hours

Coffee Maker (1300 W) : 0.8 H
Electric Cooker (900 W) : 1.2 H
Television (60 W) : 17.9 H

Customer Review

“ This easily met my initial requirements. Easy to set up. The Initial. charging was very smooth. Looking forward to using the solar charge feature. My backup for my CPAP equipment and more In the future.” — James Kroupa.

Electric Power Formula FAQs

How do you calculate power?

Power is calculated using this formula : P = V * I, where V is the voltage in volts, P is the power in watts, and I is the current in amperes.

What is the formula for electric energy?

Energy = Power x Time. Energy is measured in Joules, power is measured in watts, and time in seconds.

What is the formula for power in watts?

The power formula in electricity is Power (in watts) = Voltage × Current.

What is Watt's law?

Watt's law describes the relationship between power, voltage, and current, stating that power in a circuit is the product of voltage and current. The formula for power in electricity is P = V * I.

How many watts is 220 volts?

It depends on the amps in the circuit. Here is a table that reveals the watts calculated if the volts are 220 V and the amps are 1 A.




220 V

1 A

220 W

220 V

2 A

440 W

220 V

3 A

660 W

220 V

4 A

880 W

220 V

5 A

1100 W

220 V

6 A

1320 W

220 V

7 A

1540 W

220 V

8 A

1760 W

220 V

9 A

1980 W

220 V

10 A

2200 W

Final Thoughts

Electric power is crucial for any battery operation and everyday use. The power formula for electricity demonstrates how voltage and current are related to one another. In this regard, Jackery Solar Generators are a perfect solution for sustainable power, reducing grid dependence and utility bills. What sets these power stations apart is their ability to deliver uninterrupted power supply during emergencies, support various devices, and help people save energy resources.

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