# Physics - Everyday Electrical Transfers (AQA Syllabus A)

Electrical energy is one of the topics looked at in GCSE Science. This is the first of six quizzes on that particular subject and it looks at transfers of electrical energy in everyday domestic appliances.

When you consider all the everyday appliances that run off electricity, like light bulbs, TVs, refrigerators, CD players, radios, computers, vacuum cleaners, microwaves, the internet etc, it's hard to imagine life without electricity. Think of how important they are in your life - music/TV/Internet on demand, ice cream staying solid in the freezer, light to read by in the evening. Put simply, the convenience and usefulness of mains electricity to our way of life and standard of living is major.

Electricity is a convenient form of energy that can be converted easily into many other forms of energy and made to perform various useful tasks. Yes, there are alternatives to many household appliances but they usually involve some kind of hard work or sacrifice. Take for example an everyday vacuum cleaner. This takes electrical energy and transfers it into useful kinetic energy, saving the hard work of taking up a carpet and beating it clean for several hours. It also wastes some of the electrical energy, producing heat and sound energies - but that is for another quiz!

For the exam, you are expected to know examples of energy transfers that electrical appliances are designed to make; compare the advantages and disadvantages of using different electrical appliances for a particular application; how to reduce your consumption of electrical energy; and, of course, the principle of conservation of energy...

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1. A wind-up radio was invented to help people living in communities where it is not always possible to buy batteries. Which of the following represent the main energy changes in such a device?
The operator uses a handle to tighten a spring that powers a clockwork mechanism. When the spring is released, the clockwork mechanism turns a small generator to produce the small electrical current that powers the radio
2. Which of the following represents the energy transfers in a food mixer?
OK, if there is an LED indicator or small lamp to show it's on, there is light energy too!
3. An air source heat pump is an electrically powered device that recovers heat energy from the air. For every kilowatt of electrical energy used, it provides three kilowatts of heat energy. Some homes are heated using a heat pump. Which of the following is not an advantage of using such an appliance when compared with the alternative of using a fossil fuel powered boiler?
Using any central heating system neither wastes time nor saves time. Since it is efficient, it reduces the amount of energy used by a home, which is good for the environment and saves money at the same time
4. What are the alternative names of the energy of movement, thermal energy and radiant energy which are all types of energy that are transferred from electrical energy by domestic appliances?
You are quite likely to see these alternatives used in exam questions
5. What is the energy transfer that an electric guitar is designed to make?
You have British scientist Michael Faraday to thank for this - he discovered that moving a wire in a magnetic field transferred kinetic energy into electrical energy. The guitar strings vibrate (kinetic energy) and as they move past the magnetic pickup, a small electrical current is generated. This can then be transferred into sound using an amplifier and loudspeaker
6. What are the two most common forms of waste energy?
All electrical devices produce heat which spreads out into the surroundings. Electrical devices with moving parts also create sound energy, which is normally a waste energy
7. Digital mp3 players have almost completely replaced portable CD players. When you compare the energy transfers, which of the following types of energy is found in one but not the other?
The energy transfers of a CD player are electrical to heat, kinetic (to spin the CD round) sound and light (to display track information). Nothing needs to be moved to create the music in an mp3 player
8. In developing countries, many homes do not yet have a source of mains electricity and need to rely on batteries. Batteries store which type of energy?
The chemical energy is transferred into electrical energy by the chemical reactions that take place when the battery is connected to a complete circuit
9. Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed. In the context of the above sentence, dissipated means what?
The second and third answers are partially true but the first one takes care of every case
10. When energy has been dissipated, it:
Because it is now so spread out, it is very hard to use it for anything else