Electricity - Spigot Science

Science ConnectionTwo Typesof FlowingElectricityBy David CochranKelly Martin, Wikimedia CommonsAn electrical substation where AC current flowsThere are two types of electricity that flowthrough electric circuits―direct current and alternatingcurrent.1. Direct Current (DC)Direct current is the type of current in a battery.One end of the battery holds a positive charge andthe other a negative charge. To power a light bulb,one end of a wire is connected to the positive endand the other end is connected to the bulb. A secondwire is connected from the negative side of the batteryand to the light bulb. Electricity is stored in thebattery. When the wires are connected, it completesa circuit, a round trip for the electrons from the batteryto the light and back to the battery. Direct currentis only good when lower voltage is needed.See How to Make a Graphite Circuit on page 12.2. Alternating Current (AC)The type of electric current that we use most oftenis called alternating current. It is used whenhigher voltage is needed and when voltage levelsneed to be adjusted from higher to lower. A generatoris needed to create alternating current. It worksby alternating or changing the direction of the currentmany times per second. When electricity comesfrom a large generator, it is too powerful to be usedsafely in our homes. It needs to be stepped down to aless powerful level using a transformer. By alternatingthe current, it is easier to adjust it for variouspower needs. A factory may need a lot of power,while a small house may need much less.Activities1. Read more about the direct and alternatingcurrent in books or on the Internet. Create adiagram that shows how each works. Be preparedto explain and discuss your diagram.2. Search on the Internet to find out how we cancharge DC devices by plugging them into an ACoutlet in the wall. Discuss your answer withothers.3. Do research and build a list of devices that useAC and DC. Explain what the items on each listhave in common. Why do you think the items havedifferent power requirements?Spigot Science - http://www.spigotscience.com 6 Electricity