ClassX Video Lessons Youtube Channel The Engineering Mindset What is a kWh – kilowatt hour + CALCULATIONS ???????? energy bill
Hello everyone! Today, we’re diving into the world of electricity to understand what a kilowatt hour (kWh) is. We’ll explore terms like watts, kilowatts, and joules, and learn how to convert between them. Plus, we’ll go through some examples to help you calculate your electricity usage and monthly bill.
When you look at your electricity bill, you’ll see the amount of kWh you’ve used. But what does that mean? A kilowatt hour measures how much energy you use over time. It’s calculated by multiplying power (in kilowatts) by time (in hours).
Electrical devices are rated in watts (W) or kilowatts (kW). For example, an air heater might use two kilowatts, while a light bulb might use 100 watts. The term “kilo” means 1,000, so one kilowatt equals 1,000 watts. A watt is a unit of power named after James Watt, and one watt equals one joule per second. A kilowatt hour is equivalent to 3.6 million joules.
A joule is a unit of energy. It’s the energy used when one ampere of current passes through a resistance of one ohm for one second. In simpler terms, it’s a way to measure energy, similar to how we measure food energy in calories.
To convert kilowatts to watts, multiply by 1,000. For example, 1 kW equals 1,000 W. To convert watts to kilowatts, divide by 1,000. So, 100 W equals 0.1 kW.
To find out how much electricity a device uses, you need to know its power rating and how long it’s used. For example, if a heater uses two kilowatts and runs for three hours, it uses 6 kWh (2 kW x 3 hours). If it runs for 30 seconds, convert seconds to hours (30 seconds is about 0.0083 hours), then multiply: 2 kW x 0.0083 hours = 0.0167 kWh.
For smaller devices like a 60-watt light bulb running for 10 hours, first convert watts to kilowatts: 60 W / 1,000 = 0.06 kW. Then multiply by the runtime: 0.06 kW x 10 hours = 0.6 kWh.
To find out the cost, multiply your kWh usage by the rate your electricity company charges. For example, if your heater uses 6 kWh and the rate is 10 cents per kWh, the cost is 6 kWh x $0.10 = 60 cents.
To estimate your monthly electricity usage, list all your electrical devices, their power ratings, and how many hours per month they’re used. Calculate the kWh for each device and add them up for the total monthly usage. Then, multiply by your electricity rate to find the cost. Remember, your bill might include extra charges like taxes.
That’s all for now! I hope this helps you understand kilowatt hours and how to calculate your electricity usage. If you have any questions, feel free to ask. Don’t forget to check out more resources at TheEngineeringMindset.com.
Find five electrical devices in your home and note their power ratings in watts or kilowatts. Record how long each device is typically used in a day. This will help you understand the concept of power ratings and their impact on energy consumption.
Using the devices you found in the scavenger hunt, calculate the daily kWh usage for each. Multiply the power rating by the hours used and convert to kilowatt hours if necessary. Share your findings with the class to compare energy usage.
Estimate your household’s monthly electricity usage by listing all devices, their power ratings, and usage hours per month. Calculate the total kWh and estimate the cost using a given electricity rate. Discuss how you might reduce energy consumption.
Work in pairs to convert a list of devices’ power ratings from watts to kilowatts and vice versa. Time each other to see who can complete the conversions fastest. This will reinforce your understanding of unit conversions.
Research how joules and calories are used to measure energy. Create a poster comparing the two units, including examples of how each is used in everyday life. Present your poster to the class to enhance your understanding of energy measurement.
Sure! Here’s a sanitized version of the transcript:
—
Hello everyone, Paul here from TheEngineeringMindset.com. In this video, we will explore what a kilowatt hour is. We will cover kilowatt hours, watts, kilowatts, and joules, as well as how to convert between watts and kilowatts. Additionally, we will calculate your kilowatt hour usage with some examples towards the end, and discuss how to calculate your monthly electricity bill.
You may have noticed that your electricity bills show the amount of kWh you have used. When you purchase electrical goods, they are rated in watts (W) or kilowatts (kW). Your electricity bill is based on kilowatt hours (kWh), which indicates how much power was consumed over a period of time. The formula for energy is power multiplied by time.
Let’s briefly define a kilowatt. The electrical goods you purchase will have a value in watts or kilowatts, indicating their power demand. For example, an air heater may be rated at two kilowatts, while a light bulb might be rated at 100 watts. The prefix “kilo” means 1,000, and a watt is a unit of power named after the engineer James Watt. Specifically, one watt is equal to one joule per second, and a kilowatt hour is equivalent to 3.6 megajoules.
A joule is a unit of energy transferred to perform work. Our food contains energy measured in joules or calories, which we consume to fuel our bodies. In electrical terms, a joule is the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second.
If you want to learn more about the basics of electricity, you can watch one of our other videos on how electricity works. The link is available in the top right corner of the screen or in the description box below.
To convert kilowatts to watts, simply multiply by 1,000. For example, one kilowatt multiplied by 1,000 equals 1,000 watts. Conversely, to convert watts to kilowatts, divide by 1,000. For instance, 100 watts divided by 1,000 equals 0.1 kilowatts.
To determine how much electricity a heater will use, we need to know its power demand and how long it will be on. If the heater is rated at two kilowatts and runs for three hours, the calculation would be two kilowatts multiplied by three hours, resulting in six kilowatt hours. If the heater runs for only 30 seconds, we can still use the energy formula, but we need to convert seconds into hours. There are 3,600 seconds in an hour, so 30 seconds is approximately 0.0083 hours. Therefore, two kilowatts multiplied by 0.0083 hours equals 0.0167 kilowatt hours.
For smaller items rated in watts, such as a 60-watt light bulb running for 10 hours, we again use the formula energy equals power multiplied by time. First, convert watts to kilowatts: 60 divided by 1,000 equals 0.06 kilowatts. Then, multiply by the runtime of 10 hours to get 0.6 kilowatt hours.
To calculate the cost, multiply the kilowatt hour consumption by the electricity tariff set by your supplier. For example, if the heater fan is two kilowatts and runs for three hours, that’s six kilowatt hours. If your electricity company charges 10 cents per kilowatt hour, then six kilowatt hours multiplied by $0.10 equals 60 cents.
To calculate your monthly electricity consumption, create a table of all electrical items in your building, noting their power ratings. Remember to count how many of each item you have and ensure they are rated in kilowatts. Then, calculate how many hours per month each item will be used. Use the energy formula for each item and sum the values in the energy column to get the total kilowatt hour consumption for the month. Once you have this total, you can calculate the cost. Keep in mind that there may be additional costs on your supplier’s invoice, such as taxes.
That’s it for this video! I hope you found it helpful. Don’t forget to like, subscribe, and share. If you have any questions, please leave them in the comment section below. Also, check out our website at TheEngineeringMindset.com.
—
Let me know if you need any further modifications!
Kilowatt – A unit of power equal to 1,000 watts, commonly used to measure the output of engines and the power of electric motors, tools, and heaters. – The electric heater in our classroom uses 2 kilowatts of power to keep us warm during winter.
Hour – A unit of time equal to 60 minutes, used to measure the duration of events or processes. – The physics experiment took about one hour to complete, allowing us to observe the changes in temperature.
Watts – A unit of power in the International System of Units (SI) that measures the rate of energy transfer equivalent to one joule per second. – The light bulb in the lab consumes 60 watts of power when it is turned on.
Joules – A unit of energy in the International System of Units (SI) that measures the amount of work done when a force of one newton displaces an object by one meter. – The battery in the remote control stores energy measured in joules.
Energy – The capacity to do work or produce change, often measured in joules or kilowatt-hours in physics and engineering. – Solar panels convert sunlight into electrical energy to power our homes.
Power – The rate at which work is done or energy is transferred, often measured in watts or kilowatts. – The power of the motor determines how quickly it can lift the elevator.
Calculate – To determine the amount or number of something mathematically, often used in physics to find values like speed, force, or energy. – We need to calculate the speed of the car using the distance and time measurements.
Usage – The amount of something consumed or utilized, often referring to energy or resources in engineering. – Monitoring the electricity usage in our school helps us find ways to save energy.
Convert – To change something into a different form or system, often used in physics to change units or types of energy. – We can convert mechanical energy into electrical energy using a generator.
Electricity – A form of energy resulting from the existence of charged particles, used to power devices and machines. – The electricity generated by the wind turbine is used to light up the entire building.
