Energy, Electricity, and Magnetism

What is energy?

What is energy? A. The ability to move an object over a

distance.B. The ability to do work

Law of Conservation of Energy?

Types of Energy

• Chemical• Stored Mechanical• Mechanical• Gravitational• Potential • Kinetic• Nuclear• Radiant• Thermal • Electrical• Sound

How can we manufacture energy?

• Fossil Fuels• Biomass• Solar• Hydroelectric• Wind• Geothermal• Nuclear• Renewable resources are materials that can be replaced

through natural and/or human processes. • Nonrenewable resources exist in fixed amounts within the

earth and once they’re used up, they’re gone forever or it takes the earth an extreme amount of time to make them.

Fossil Fuels

• Coal, Petrol, Natural Gas• Formed during the CARBONIFEROUS period,

organisms (like algae/zooplankton) exposed to heat and pressure- but not air

• Coal- Mine• Natural Gas- Frack (drill, pump in water

solution, capture escaping gas from shale, repeat)

• Petroleum/ Crude Oil- Drill and refine into different combinations of hydrocarbons

Biomass

• Energy derived by processing once living things, most often collected, burned to heat directly or to heat water and turn a turbine for electricity

• Biodiesel/ ethanol- Corn and algae• Petrol- algae• Methane- manure • Direct Fuel- wood/ plant matter (burning)

Solar

Photovoltaic and Thermal

• Photo- photons- light to make energy (DC current)

• Thermal- heat, Water is heated and Energy is transferred to heat other water sources

Hydroelectric, Wind, Geothermal

• Why did I place these all together… TURBINES!Water, air or steam move the blades of the

turbine and generate the charge needed for electricity

• A turbine takes motion (mechanical energy) and generates it into electricity.

It a GENERATOR (which we will discuss again later)

Nuclear

• This involves steam rotating turbines but HOW?• Core or radioactive substance (usually Uranium),

immersed into pools of water• Undergoes the process of fission, atom decays into

“smaller elements”• During this process, energy in the form of heat is

released and creates steam which turns a steam turbine

• These are in pressurized systems and can be activated or cooled off. If it can not be cooled off properly = “meltdown”

Units for energy and electricity

• joule (J) -The SI unit of energy (work) . 1kg ·m2 /s2

What else is a joule?

Units for ElectricityJoules are also…

*Work necessary to move an electric charge of one coulomb through a volt

Coulomb- SI unit of Electric charge, one amp in one sec (C or a * s)Volt- electric potential energy between 2 points, “difference” (V)

*Work required to produce one watt of power for one sec

Watt- SI unit for power, J/s, power is the rate of doing work (W)

• KwH- kilowatt hours• 1 kilowatt hour = 3.6×106 J (or 3.6 MJ)

Ampere Amp- The amount of electric charge passing specific point in an

electric circuit per second

The measure of rate of flow of electrons.

I can change this by-

-increasing the number of charged particles -the charge on the particles-the speed at which the particles are moving past a specified point

1A= C/S

Ohm’s

• The ohm (Ω) is the SI unit of resistance

• Ohm’s Law- a current through a conductive material between two points is directly proportional to the potential difference (volt).

Current (I) = Voltage Resistance

Current- represented by I or A (in amps)

WRITE THIS DOWN!!

Practice Problems

• In a circuit there is a 0.5 A current in the bulb. The voltage across the bulb is 4.0 V. What is the bulb’s resistance?

• A waffle iron has a 12 A current. If the resistance of the coils is 10 Ω, what must the voltage be

Tools to measure

• Multimeter• Voltmeter

Galvanometer, an instrument used to indicate the presence, direction, or strength of a small electric current through movements of a magnetic needle in a magnetic field

What is Electricity?• Electricity is the movement of electrons, flows from a negative charge to a positive

• Static stays in one place, is created when an object gives up or gains electrons, moves from one surface to another

• Rubbing an inflated balloon on clothing or rubbing your shoes on carpeting forms static electricity. Lightning is also static!

• Electrical is a flow of electric charge, often carried by moving electrons in a wire.

• (It can also be carried by ions in an electrolyte, or by both ions and electrons in a plasma)

Transferring Charges:

Friction: the transfer of electrons from one uncharged object to another by rubbingConduction: the transfer of electrons from a charged object to another by direct contactInduction: creating voltage in a conductor when exposed to a magnetic force

Conductors and Insulators

• Material from which the wire is made.

Insulators = high resistance • Glass, Plastic Wood

Conductors = low resistanceMetals (copper, silver), ionized solutions

Length, diameter and temperature can affect resistance

Magnets and Electromagnets

Magnet- material which has a field which attracts other magnetic objects- ferrous materials

A magnet produced by an electric field is called an electromagnet.

A coil of wire with a current is called a solenoid.OPPOSITES ATTRACT!

3 characteristics of a magnetic field produced by a current:

1. The magnetic field can be turned on or off How? Turn the current off

2. The magnetic field can have its direction changed

How? Reverse the direction of the current

3. The field can have its strength change How? By winding a wire with a current into loops, you strengthen the magnetic field in the center of the coil.

• An electric current is induced (or caused) in a conductor when it moves through a magnetic field. This is called electromagnetic induction.

• In an induced current, charges may flow in one direction or may alternate (go back and forth). DC (direct current) go in one direction. AC (alternating current) go back and forth.

• AC current (alternating current) is used in homes, schools and other buildings because it can be “stepped down” for safer use. Anything with an “outlet/plug”

• DC current (direct current) is used in batteries and anything battery-powered.

Motors vs. Generators

• When electromagnets move a rod or axle (which move something like the blades of a blender) this is called an electric motor.

• A device that transforms mechanical energy into electrical energy is called a generator.

• A generator use motion in a magnetic field to produce an electric current.

• Notice: An electric motor is a device for transforming

electrical energy into mechanical energy; an electric generator does the reverse. It converts mechanical energy into electricity.

A transformer is a device that increases or decreases voltage. A transformer takes in electricity at a higher voltage and runs it through a wire with fewer coils. Having fewer coils means less voltage. So the voltage is "stepped-down.“

Electric Circuit

• Is the complete unbroken path through which an electric charge can flow

• Series and Parallel

• Circuits need an energy source- batteries or generators

Series

• Series Circuit: in a series circuit there is only one path for the current to take

Parallel

• Parallel Circuit: in a parallel circuit, the different parts of the circuit are on separate branches

Batteries

• Wet Cell

• Dry Cell