Physical Science Unit 8, Magnetism Electromagnetic Induction : a means of generating Alternating Current (AC)

Electromagnetic Induction When a wire is moved into a magnetic field, current is induced to flow in the wire If the wire is then pulled out of the field, current flows in the opposite direction If the wire is stopped in the field, current stops flowing Current flows only when the wire is moving (or “cutting magnetic field lines”)

EM Induction (cont.) To get more current, use more wire and move it faster in the field. To get even more current, use a coil of wire and spin the coil in the field. From this, get current that flows first in one direction, and then the other. Since the current alternates in direction, it is called Alternating Current (AC)

EM Induction (cont.) To generate AC electricity, we need to spin a loop of wire that is suspended in a magnetic field Electric generators operate this way Sometimes gasoline is used to spin the loop (portable generators running on construction sites, or as back-up power sources schools, in hospitals, etc.)

Large Scale AC Generation To generate large amounts of AC electricity, we need to spin large coils very quickly Power plants in this country generate large amounts of electricity using various types of mechanical forces Goal is to spin a coil of wire in a magnetic field, which generates AC electricity.

Ways to Spin the Coil of Wire 1)By projecting steam through a turbine. This is the major way (right now) that electricity is generated in this country 2)Water falling through a water wheel (called a turbine) spins the coil. This is called hydroelectric power. 3)Wind blowing through a windmill. Wind can be “harvested” and made into electricity in wind farms.

Steam (to move turbine) is produced by: Burning coal. Large-scale coal plants produce vast amounts of electricity Burning natural gas. Sometimes in co- generation, or combined cycle plants. Nuclear reactions, in nuclear power plants Turbines could also be spun by: -Biogasoline- tidal waves -Sun’s rays-wind currents -water currents

What is Biogasoline? A non-petroleum gasoline Made by algae (a living biomass) Composed of hydrocarbons (hexane and dodecane) Can be used by internal-combustion engines Info from

Renewable vs. non-renewable RenewableNon-renewable Wind Solar Geothermal Water Coal, fossil fuel Oil, fossil fuel Wood and Biomass (takes more than 10 years to replace) Natural Gas Nuclear