Electrical Power: How to Calculate, Power Energy Formula with Sample Questions

Electrical Power Formula Overview 

Electric power is a physics term that describes the rate of electrical energy transmission by an electric circuit per unit of time. It is indicated by P and measured in watts, or one joule per second, the SI power unit. Electric power is often provided by batteries and generated by generators.

Electric Power Formula: Definition

Electric power is the rate at which effort or energy is turned into an electrical circuit. It is a measurement of how much energy is consumed in a certain period of time. Electric power is a commonly used phrase in physics. Furthermore, it is critical because it allows us to see the pace at which electrical energy moves from an electric circuit. As a result, it aids us in determining the effectiveness of the same. Similarly, one may discover all about the electric power formula right here. 

Electric power, like mechanical power, is the rate at which work is done. However, in our country, we measure it in watts. Furthermore, the term wattage is used colloquially to refer to electric power measured in watts. Furthermore, companies and homes often obtain this supply from the electric power sector via an electric power grid. Electrical power provides energy with low entropy. It may also be transported across large distances. It may also convert to other forms of energy such as light, motion, or heat.

Electric Power Formula: Highlights

The following table describes the details of Electric Power-

Electric Power Formula

Electric power is defined as the rate at which energy is transferred to or from a component of an electric circuit. A battery or a circuit part, such as a resistor that releases energy as heat, can provide energy. The power of any circuit element is equal to the difference in voltage across the element multiplied by the current. Furthermore, it is critical to understand that a Watt Equals Joule per second. (1 W = 1 J/s). Therefore, the formula for electric power is as follows-

where,

P = Electric Power

V = Potential Difference or Voltage

I = Electric Current

The word power may alternatively be written as

The above two phrases are derived from Ohm's law, which states that voltage, current, and resistance are connected by the following relationship-

Where,

R = Circuit's resistance.

V = Potential Difference or Voltage

I = Electric Current

Electric Power Formula Derivations

Power is the pace at which labor is done, while electric power is the rate at which electric energy is transferred. Electric energy is created by converting the kinetic energy of charged particles into potential energy.

The positive and negative terminals of an electrolytic battery are anode and cathode. The potential difference created between two terminals by the passage of electrons is known as emf (electromotive force) or voltage in layman's terms.

Electrical Power Formula Calculator

To compute the electrical power, one has to specify the item's current, voltage, and power factor. The voltage for devices connected to electrical outlets is just the voltage of domestic power. The current drawn by the device can usually be found either marked on a plug or somewhere on the device. The power factor is a bit trickier unless one has a power quality analyzer. The following list is for the power factors of a few typical household devices-

1. Lamps with a standard bulb- pf = 1.
2. Fluorescent lamps- pf = 0.93.
3. Common induction motor- pf = 0.73 (at half load) and pf = 0.85 (at full-load). 
4. Electric oven (with resistive heating element)- pf = 1.0.
5. Inductive oven- pf = 0.85.

The power factor's exact value depends on the construction details, so take these values with a grain of salt.

Read Recently wriiten Article on Uses of Electricity and Electrical Insulator.

How to Calculate Current Using Ohm's Law

For example:- The battery voltage is 10 volts and the light resistance is 500Ω. Using Ohm's Law to calculate current, we obtain-

I = E/R

I = 10 V/500Ω

I = 0.05 A

Now that we have the current, we can multiply it by the voltage to get the power-to-weight ratio.

P = 1E = (0.05 A) (10 V) = 0.5 W

Read more about the Electric Charge Formula, Working Principle of transformer, and EMF Equation of DC Generator.

Electric Power Formula Sample Questions

Try the following application problem based on the information provided above-

Sample 1- A 6V battery is linked to a resistor with a resistance of 8 What is the current and power flowing through the resistor?

Solutions- I = V/R = 6/8 = 0.75 A

P = VI = 6 x 0.75 = 4.5 J/s or 4.5 W

Sample 2 - Calculate the electric power of a circuit with a current of 8 amps and a voltage of 34 volts.

Solution- In this case, the current flowing in the circuit (I) = 8 A

The potential differential throughout the circuit = 34 V

According to the electric power formula,

P = IV

P = 8 x 34

P = 272 watts

As a result, the circuit consumes 272 watts of power.

Things to Keep in Mind

1. The pace at which electrical energy is transported across an electric circuit is referred to as its power.
2. Power is denoted by P. 
3. Watt is the SI unit of power.
4. Power formulae are as follows: P = IV, P = I²R, and P = V²/R.
5. If one joule of electric energy flows in one second, one watt of power is spent.
6. Kwh is the commercial unit of electricity.
7. 1 kwh = 36 x 105 Ws or Joules is the electrical power conversion.