KS 3 How electricity transfers energy

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  • + Zahid95 Zahid Rahman 2 weeks ago
    Thanks a lot dude, this really helped me with my learning assessment task, I really needed to find out what they meant by energy transfer, turns out I’d already learned it, it’s just 'energy transfer in circuits' seriously confused me lol, thanks again bro
  • + scienceinteractive Dr Samuel Aylward 2 years ago
    The UK government and The European Union is right to ban the sale of normal tungsten filament light bulbs from 2011. Most of the heat produced by these items is unwanted in most houses and therfore ’lost’ to the surroundings, the effect being most dramtic when outside tempeartures are anything above 15oC, which in sunny England is a least half of the year. Not often is our government right but on this one well ’blue sky thinking all round...now just be honest about your expenses and and the public would view you as a reasonable lot !!!!
  • + guest3bf9f8 guest3bf9f8 2 years ago
    'Contributes heat?' Are you nuts. Maybe in the arctic circle, but for the rest of us, and for most of the year, heat from lighting is waste energy, and we spend additional energy to remove it (AC and fans). Even where we don’t spend energy removing it, it is absolutely not something sought after.
  • + guest13b728 guest13b728 2 years ago
    very good slide show thanks for the help
  • + guestfb52a4 guestfb52a4 2 years ago
    It would be helpful if you didn’t refer to the heat from a light bulb as a 'loss to the surrounding' and in so doing contribute to the continued ignorance of our population. Yes, it is a loss in terms of the lighting application but not usually in terms of the system in which it is a part. In most interior lighting situations, the heat from a light bulb contributes to the heating of the environment in which it is being used and reduces the amount of heat required from a central heating system by a like amount. Your non-system thinking is the reason traditional light bulbs are being banned in favor of CFBs. By the way, the same flawed thinking appies to ’energy efficient’ appliances as the heat from a TV also heats its surroundings. The cost of ignorance is high, please don’t contribute to it.

  • + guest5d4623 guest5d4623 3 years ago
    Thank you very much :)

  • + guest160118 guest160118 3 years ago
    Thankyou, you helped me with this god damned Science assesment task

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KS 3 How electricity transfers energy - Presentation Transcript

  1. lesson 9I Electricity and energy...How electricity transfers energy Science Interactive LTD. PO BOX 50764 LONDON NW6 9AT email: sales@science-interactive.co.uk web: www:science-interactive.co.uk
  2. Using electrical energy Electrical energy is cheap , easy to transport , clean at the point of use and relatively safe to use. It is also easily converted into other forms of energy by household devices like bulbs, toasters, televisions and heaters. In a circuit, free electrons move creating a flow of electricity. In a simple circuit, a battery supplies the energy to the moving current so that a device like a bulb or a motor can do useful work. Electrons are not destroyed or used up when they pass through a device, simply the energy they carry is converted into another form of energy. Energy transfer inside circuits: - - - - Free electrons Science Interactive LTD Copyright 2005 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - In a light bulb filament, 3 billion free electrons flow through the tungsten filament every billionth of a second. These electrons carry electrical energy which is then converted into light and heat energy by the bulb filament. Notes Diagram The simple light bulb Current flow in a simple circuit
  3. The rate of transferring energy, called power (watts), is measured in joules per second. A 60 watt light bulb transforms electrical energy to heat and light at the rate of 60 joules per second. Similarly, a 3 kilowatt heater transfers electrical energy to heat and light energy at the rate of 3000 joules per second. A simple equation tells us how much electrical energy in joules a device uses over a certain amount of time: Energy transferred (joules) = Power (watts) x time (seconds) Energy transfer: Energy transfer in circuits one Science Interactive LTD Copyright 2005 1500 joules of electrical energy are transferred into heat, sound and kinetic energy by the hair dryer every second. 1.5KW hair dryer 500 joules of electrical energy are transferred into light energy only by the plasma toy every second. 500W plasma light Notes Diagram 2 kilojoules of electrical energy are transferred into heat and sound energy by the kettle every second. 2 KW kettle 3 kilojoules of electrical energy are transferred into heat and light energy by the electric heater every second. 3KW heater
  4. Electrical energy is easily converted into other forms of energy. In a circuit, a flow of electricity carries electrical energy which is then converted into other forms of useful energy by household devices like bulbs, toasters, televisions, laptops and heaters. During energy transformation, some energy is lost to the surroundings, for example a bulb converts electrical energy to heat and light energy. Only the light energy is useful with the heat energy being lost to the surroundings. In the following examples, the useful energy is underlined. Energy transfer: Heat and sound energy Light , sound and heat energy Heat , kinetic and sound energy Electrical energy Electrical energy Electrical energy Kettle Hair dryer Energy transfer in circuits two Science Interactive LTD Copyright 2005 Laptop Device Notes: Consider the kettle. It runs on 2000 watts (2000 joules per second) and transfers 1900 joules per second into heat and the rest into sound energy. This energy transfer can be shown as a diagram. Energy transformation/energy out Electrical energy in
  5. When energy is transformed into another form by a device like a toaster, motor, bulb, buzzer or bell, some useful energy is lost to the environment. The efficiency of a device can be worked out using the following formula. Energy efficiency = Useful energy out/total input energy x 100 (units %) Look at the following examples, the useful energy is underlined. Energy transformations: 11 joules of light energy 1 joule of heat energy 650 J of heat energy 25 kJ of sound & light energy 75 kJ of heat energy 250 J of kinetic energy 12 J of electrical 1000 J of electrical 100 kJ of electrical Science Interactive LTD Copyright 2005 100 J of sound energy Energy transfer in circuits three Work out using the formula, the energy efficiency of a plasma television ? Three Useful energy (red) Calculation: 650J + 250J/1000J x 100 = 90% Two One Example Energy in Device Calculation: 11J/12J x 100 = 91.6% Energy efficiency
  6. 60W 150W Energy transfer in circuits four Science Interactive LTD Copyright 2005 Energy transfer diagrams show the relationship between the input energy and the output energy of a device like a games console, vacuum cleaner and light bulb. During all energy transformations, some energy is lost to the surroundings, for example a vacuum cleaner converts 500 joules of electrical energy to 300 joules of kinetic energy and 200 joules to heat and sound energy. Only the kinetic energy is useful, with the heat and sound energy being lost to the surroundings. In the following examples, the useful energy is underlined. Energy transfer inside circuits: 150 J 120 J heat 30 J light electrical 50 J heat electrical 300 J kinetic 50 J sound 50 J heat electrical 300 J kinetic 50 J sound electrical 150 J heat 500 J 100 J 15 J sound 35 J light Every second, a light bulb converts 120 joules of electrical energy into heat and 30 joules into light energy. The heat energy is lost to the surroundings. Every second, a Dyson converts 500 joules of electrical energy into 300 joules of kinetic energy, 50 joules into sound and 150 joules into heat. The heat and sound energy is lost to the surroundings. Every second, a games console converts 50 joules of electrical energy into heat, 15 joules into sound and 25 joules into light. This heat energy is lost to the surroundings. Notes Light bulb (150W) Dyson (500W) Transfer Diagram Js -1 Diagram Console (100W)

+ Dr Samuel AylwardDr Samuel Aylward, 3 years ago

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