Electricity is what makes our world go round. It's all thanks to Nikola Tesla and his discovery of alternating current (AC) power that we're able to power our homes with electrical power. But, what exactly is electrical power and how does it work? In this article, we'll explain everything you need to know about electrical power, including its definition, equations, and properties. We'll also explore the relationship between power, current, voltage, and other important factors. So, get ready to learn all about electrical power!

Electrical power definition

Electric power is the amount of electrical energy transferred in a circuit per unit of time. The unit of electric power is the Watt (), which is often measured in. The power rating on home appliances tells us how much energy is being used to power the device. For example, a mobile phone charger has a power rating in the range of, drawing orJoules per second from the mains. In contrast, an electric kettle has a power rating of, which is times the power consumed by a mobile charger, making it much more expensive to use. To calculate power, simply multiply the current drawn by the voltage.

Electrical power formula

To calculate the electric power transferred to an electrical component in a circuit, use the formula:

This means that electric power () equals potential difference () multiplied by current ().

Alternatively, you can also calculate electric power by using the formula:

where () is the resistance of the component.

In other words, electric power is defined as the energy transferred when a current of () flows through a potential difference of ().

Electrical power triangle

The electric power triangle is an easy way to memorize the above equation. This formula can be rearranged with the help of an Electrical power triangle shown below.

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The second electrical power formula can be derived using Ohm's law, which states that the potential difference across a conductor is directly proportional to the current passing through it, given a constant resistance. The equation for Ohm's law is:

Substituting the value for potential difference into the equation for electric power, we get:

or in words:

Let's look at a few examples of how to calculate power:

Example 1: An appliance is supplied by a 110V supply, with a current of 2A flowing through a speaker of resistance 20Ω. Calculate the power rating of the speaker.

Step 1: List out the given quantities:

• Potential difference () = 110V
• Current () = 2A
• Resistance () = 20Ω

Step 2: Choose the right equation for calculating power.
We have the values for current and resistance, so we can use the following equation:

So, the power consumed by the appliance is:

Example 2: Calculate the potential difference across an electric motor with a current of 5A and an electric power of 750W.

Step 1: List out the given quantities:

• Current () = 5A
• Electric power () = 750W

Step 2: Choose the right equation for calculating the potential difference.
We have the values for current and electric power, so we can use the following equation:

So the potential difference across the electric motor is:

Example 3: Calculate the power transferred when a current of 10A passes through a conductor of resistance 2Ω.

Step 1: List out the given quantities:

• Current () = 10A
• Resistance () = 2Ω

Step 2: Choose the right equation for calculating power.
We have the values for current and resistance, so we can use the following equation:

The power being transmitted is: Therefore, the power transferred is 100W.

Power transmission

The power consumed by an electrical component depends on both the magnitude of the current passing through it and the potential difference across it. Therefore, the same amount of electric power can be delivered using different combinations of potential difference and current.

One way to deliver a certain amount of power is to use a low current with a high voltage. This is commonly used in power transmission over long distances, where high voltages are used to reduce energy losses due to resistance in the transmission lines.

Alternatively, we can also deliver the same amount of power using a high current with a low voltage. This is commonly used in applications such as electric motors, where high currents are required to generate the necessary torque to drive the motor.

In both cases, the power delivered remains the same, but the values of current and potential difference can vary depending on the specific application and the desired efficiency of the system.

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The heating effect is a major disadvantage of using high currents with low voltages. When a high current flows through a wire or any other electrical component, it experiences resistance, which leads to heating of the component. This heating effect can reduce the lifetime of the component and also reduces the efficiency of the electrical device.

The amount of heat produced due to the flow of current is directly proportional to the resistance of the wire or component. This is because the work done by the current in overcoming the resistance is converted into heat energy. Therefore, to reduce the heating effect and increase the efficiency of the electrical device, it is better to transmit high power in high voltages with low currents. This helps to reduce the resistance and heating effect, thereby increasing the efficiency and the lifetime of the electrical components.

Electrical Power - Key takeaways

Electric power is defined as the electrical energy transferred in a circuit per unit of time. Electric power or the electric energy transferred in a circuit can be calculated using the electric power formula Electric power can also be calculated using the equation The disadvantage of using a high magnitude of current with a low voltage is the heating effect. When large values of current pass through a wire they heat up to high temperatures which reduces the life of the wires leading to high maintenance costs and wasted energy. High powers across the mains are transmitted in high voltages with low currents.

Electrical Power

What is electrical power?

Electric power is defined as the electrical energy transferred in a circuit per unit of time.

What is the electrical power formula?

The electric power dissipated in a circuit by a particular component can be calculated using the electric power formula: P=IV, where P is the power, V is the potential difference drop due to the component and I is the current passing through the component.

How is electricity generated in a power station?

Electricity is generated in a power station by the combustion of fossil fuels. Water is heated until it reaches boiling temperature. The steam produced turns a turbine which powers a generator which produces electricity.

What is an SI unit of electric power?

The SI unit of electric power is the Watt and it is denoted by the symbol W.

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