1 / 11

Cost of electricity

5 January, 2020. Cost of electricity. Keywords Power, Watt, Energy, Joules, Work Done, Kilowatt, Kilojoules, kWhour, Unit. Outcomes. All students should be able to: Calculate the number of units used by a an electrical appliance. Most students should be able to:

denaj
Download Presentation

Cost of electricity

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 5 January, 2020 Cost of electricity Keywords Power, Watt, Energy, Joules, Work Done, Kilowatt, Kilojoules, kWhour, Unit.

  2. Outcomes All students should be able to: • Calculate the number of units used by a an electrical appliance. Most students should be able to: • Calculate the cost of using an electrical appliance of a certain power rating for a specific time. Some students should be able to: • Read electricity bills and compare estimates to bills and different tariffs.

  3. Power • What is power? • Power is the energy transferred in a certain time. • Power in Watts is the amount of Joules transferred in 1 second. ENERGY POWER ¦ TIME

  4. Power Challenge. • Use the dynamo connected to the dynamo to measure the energy transferred by 2 students over different amounts of time. • Record the results in a table. • Calculate who has the biggest average power.

  5. Calculating the cost of electricity Clearly, this depends on two things: the POWER RATING of the appliance and HOW LONG you leave it on for. Electricity is measured in “units”, also called “kilowatt hours” (kWh). • To work out how much something would cost use two steps: • Find out how many units have been used: • No. of units = Power rating x Time appliance is on for • in kWh in kW in hours • 2) Multiply the number of units by how much each one costs: • Cost of electricity = no. of units used x cost of each unit • in pence in kWh in pence

  6. A 3kW fire left on for 1 hour uses 3kWh of energy A 1kW toaster left on for 2 hours uses 2kWh A 0.5kW hoover left on for 4 hours uses __kWh A 200W TV left on for 5 hours uses __kWh A 2kW kettle left on for 15 minutes uses __kWh Units of Electricity Electricity is measured in units called “kilowatt hours” (kWh). For example…

  7. The Cost of Electricity To work out how much a device costs we do the following: Cost of electricity=Power (kW)xtime (h)xcost per kWh (p) For example, if electricity costs 8p per unit calculate the cost of the following… • A 2kW fire left on for 3 hours • A 0.2kW TV left on for 5 hours • A 0.1kW light bulb left on for 10 hours • A 0.5kW hoover left on for 1 hour 48p 8p 8p 4p

  8. Demo Time!! • The cost of lighting a home. • Can you calculate the cost of lighting your home for 1 day? • 1 month? • 1 year?

  9. Electrical Power • As a class we will now do questions from Milner Text book p 20-21. • In pairs do questions on p22-23. • Time Limit: 15 mins. • Peer mark.

  10. Plenary – Snowball – The Big Q: Why Be Energy Efficient? • In the back of your books jot down 3 ideas – why we should be energy efficient. • Now discuss your ideas with your partner. • Now talk in groups to see if you have all said the same things or not – In 2 minutes your teacher will pick on one of you to tell the rest of the group your ideas, so get involved!

  11. Plenary - Hotseat • 1 person sits at the front on the “hotseat” • Your teacher has a list of questions from the lesson we have done. • Answer 3 correctly – get a merit and choose the next person.

More Related