European class : 1EURO Read and answer N° 3 ( supercapacitors) SUPERCAPACITOR COULD POWER PHONE, LAPTOP FOR DAYS Scientists have created a new super capacitor that is powerful and cheap enough to replace the larger, heavier capacitors used in consumer electronics such as computers and cell phones. The new supercapacitor could be fully charged in a second and, coupled to a normal battery, provide enough energy to power a cell phone for weeks or a laptop for days. Capacitors, like batteries, store energy, but that's where most of the similarities end. Generally speaking, a battery, like the one inside your cell phone or laptop computer, stores energy chemically. That chemical energy is then converted into electrical energy. Converting electrical energy into chemical energy and vice versa is a relatively slow process, which is why the lithium-ion batteries in laptops and cell phones can last for hours or even days but also require a long time to charge. A capacitor is different. Simply put, a capacitor stores an electrical charge between two conductive plates separated by an electrical insulator. Without the chemical-electrical conversion, a capacitor can be charged and discharged much more rapidly than a battery, last longer and weigh less. Capacitors are ideal for camera flashes and other electrically intensive consumer devices. However, in contrast to batteries, a normal capacitor cannot store enough energy to power anything that lasts longer than a flash -- some fraction of a second. Supercapacitors, however, store much more energy than their traditional counterparts and are used to power small devices such as toys including model planes and helicopters.

PART 1 You have to present the supercapacitor. You can use your knowledge and information given in this text. You can use the questions below to organize or support your presentation, but feel free to use them in any order you like. Make an introduction on capacitors (constitution and unit). What similar property has a capacitor compared to a battery? What advantage has a supercapacitor on a normal capacitor? Discuss about its application concerning cell phones and laptops. - Give 2 other applications of supercapacitors and discuss briefly about the advantages of using these supercapacitors. - Conclude. -

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European class : 1EURO Read and answer N° 3 ( supercapacitors) PART 2 The electrical specifications of a supercapacitor are given: Capacitance: 0.15 F Temperature range: -25°C to +70°C Weight: 0.5 grams Maximum stored energy: 0.00063 Watt hours Maximum DC voltage = 6 V

a) Use the specifications to make a full description of the given super capacitor. b) Kilowatt hour (kWh) is a unit of energy. Give another unit of energy and convert 1 kWh into this unit. c) The voltage against time charge graph of the capacitor is given : Voltage uC (V)

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t (s)

☞ The charge of the capacitor is considered to be a linear one. Why? ☞ I = constant current through capacitor of capacitance C. Give the relationship between uC and t and tell what this relationship has to do with the line. ☞ Give the relationship of the slope of the line. ☞ The slope of the line will increase when the current I increases. Explain why?

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