Suggested languages for you: |
|

## All-in-one learning app

• Flashcards
• NotesNotes
• ExplanationsExplanations
• Study Planner
• Textbook solutions

# Electrical Power Save Print Edit
Electrical Power
• Astrophysics • Atoms and Radioactivity • Electricity • Energy Physics • Engineering Physics • Fields in Physics • Force • Further Mechanics and Thermal Physics • Magnetism • Measurements • Mechanics and Materials • Medical Physics • Nuclear Physics • Particle Model of Matter • Physical Quantities and Units • Physics of Motion • Radiation • Space Physics • Turning Points in Physics • Waves Physics Electrical power runs the world around us. Thanks to Nikola Tesla's discovery of alternating current (AC) power, homes all around the world receive Electricity. So then what exactly does electrical power have to do with the electricity that powers our appliances? This article will give you a detailed explanation of the definition of power, its equations, and its properties. We will also study the relationship between power, current, voltage, and other quantities. Happy learning!

## Electrical power definition

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

The unit of electric power is the Watt ( ) and it is denoted by the symbol . It is often measured in .

The power rating that we see in our home appliances defines how much energy is being transferred from the grid to power the device. A mobile phone charger has a power rating in the range of . This means that the charger draws or Joules per second from the mains. An electric kettle on the other hand has a power rating of . That is Joules per second which is times the power consumed by the charger! This makes it times more expensive to use than your typical mobile charger. Let us now look at how to calculate the power using the current drawn and the voltage.

## Electrical power formula

The electric power transferred to an electrical component in a circuit can be calculated using the electric power formula: Or in words: where is the electrical power, is the potential difference across the component and is the current passing through the component.

The electric power can also be calculated by knowing the current and resistance using the following equation where is the resistance of the electrical component.

Therefore, of electric power can be 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. Electrical Power Electric Power triangle, StudySmarter Originals

We can derive the second electrical power formula using Ohm's law. The equation for Ohm's law is given by We can substitute the value for the potential difference into the equation for power.  or in words Let us look at a few examples where we calculate power:

A appliance is supplied by a supply, calculate the power rating of the speaker.

Step 1: List out the given quantities , Step 2: Choose the right equation for calculating power

We have the values for current and resistance we can use the following equation So, the power consumed by the appliance is .

Calculate the potential difference through an electric motor with a current of and an electric power of .

Step 1: List out the given quantities Step 2: Choose the right equation for calculating the potential difference

We have the values for current and resistance, we can use the following equation So the potential difference across the electric motor is .

Calculate the power transferred when a current of passes through a conductor of resistance .

Step 1: List out the given quantities Step 2: Choose the right equation for calculating power

We have the values for current and resistance we can use the following equation The power is being transmitted is .

## Power transmission

For a given value of current, the power consumed increases with an increase in potential difference. The magnitude of power consumed depends on both the current and the potential difference. Therefore electric power can be delivered in the same quantity using different combinations of potential difference and current.

• Low current with a high voltage
• High current with a low voltage Warning signs outside power stations indicate that the voltages present are dangerous to humans and could cause serious harm in the form of an electric shock, StudySmarter

The disadvantage of using a high current with a low potential difference is the heating effect. When large values of current pass through a wire they heat up to high temperatures which reduces the lifetime of the wires. The heating effect is bad as it reduces the efficiency of the electric device. This is because a part of the energy that is being transferred is being converted into heat. For this reason, High powers across the mains are transmitted in high voltages with low currents.

The heating effect is due to the current passing through a resistor. The heat produced is directly proportional to the resistance of the wire or device. When current passes through a conductor it overcomes the resistance of the wire, the work done against the resistance is converted into heat.

## 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.

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

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.

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.

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

## Final Electrical Power Quiz

Question

What is the unit for electric power?

watt

Show question

Question

What is the equation for power?

P=VI

Show question

Question

If the voltage in a circuit is increased the power will ...

Increase

Show question

Question

The power rating tells us the ...

Power consumed in 1 second

Show question

Question

Power is directly proportional to the current flowing in the circuit.

True

Show question

Question

1 Kilowatt =

1000 joules per second

Show question

Question

What is the definition of power?

Power is defined as the rate of energy transfer per second

Show question

Question

High voltage or high current, which of these can heat up a wire more?

High current

Show question 60%

of the users don't pass the Electrical Power quiz! Will you pass the quiz?

Start Quiz

### No need to cheat if you have everything you need to succeed! Packed into one app! ## Study Plan

Be perfectly prepared on time with an individual plan. ## Quizzes

Test your knowledge with gamified quizzes. ## Flashcards

Create and find flashcards in record time. ## Notes

Create beautiful notes faster than ever before. ## Study Sets

Have all your study materials in one place. ## Documents

Upload unlimited documents and save them online. ## Study Analytics

Identify your study strength and weaknesses. ## Weekly Goals

Set individual study goals and earn points reaching them. ## Smart Reminders

Stop procrastinating with our study reminders. ## Rewards

Earn points, unlock badges and level up while studying. ## Magic Marker

Create flashcards in notes completely automatically. ## Smart Formatting

Create the most beautiful study materials using our templates.

Just Signed up?

No, I'll do it now