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Unit D: Electrical Principles. Topic 1: Transfer and Storage of Electrical Energy. I. Review. What is electricity?. Is the energy of charged particles. Is when electrons are moved. Remember: Electrons are the outer particle of an atom. I. Review.

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unit d electrical principles

Unit D: Electrical Principles

Topic 1: Transfer and Storage of Electrical Energy

i review
I. Review
  • What is electricity?
  • Is the energy of charged particles
  • Is when electrons are moved

Remember: Electrons are the outer particle of an atom

i review1
I. Review
  • All matter is made of particles; Particles are atoms
  • Atoms are made of 3 sub-atomic particles:
    • Neutrons – neutral (0) particles
    • Protons – positive (+) particles
    • Electrons – negative (-) particles
i review2
I. Review
  • Draw an atom!
i review3
I. Review
  • Atoms are neutral – this means :

# of protons = # of electrons

  • Being charged means having unequal protons and neutrons
    • +++ - - - -
    • + - +- -
    • - - - - -++
  • Easiest method of charging, is through friction!!!
ii static electricity
II. Static electricity

A. Laws of Electrical Charge

  • Opposite charges attract

(+ and – will attract)

  • Like charges repel (ex. + and + will repel)
activity charge it
Activity: Charge It

To witness the action of uncharged/ charged objects on each other.

 Remove charges from objects by running through your hand

 Charge objects by running through paper towel or fur

i static electricity
I. Static electricity
  • Definition: The state of having unequal number of protons and electrons ; is an UNMOVING charge
  • “static” means not moving;
  • charge DOES NOT flow constantly

(vs. current electricity where charges are flowing)

i static electricity1
I. Static electricity

A. Charge Separation

  • Occurs when a charged object is brought close to a neutral object
  • The same charges will repel, causing the opposite charges to attract
b electrical discharge
B. Electrical Discharge
  • Although static electricity does not move, it is “discharged”
  • Is the process of built up electrons transferring to other objects (Shocked!) Ex. lightning

Electric eel

Simulation

b electrical discharge1
B. Electrical Discharge
  • Discharging makes the charges between objects equal
  • [Draw objects : Before / After ]
b electrical discharge2
B. Electrical Discharge
  • Grounding – a method of discharging an object
    • Done by connecting object with a wire to the Earth (it can absorb lots of electrons)
c van der graff generators
C. Van DerGraff Generators
  • Used to study electrical discharges
  • Electrons build up on the outside sphere through friction -> the electrons seek to be discharged
what is the difference between current electricity and static electricity
What is the difference between current electricity and static electricity?
  • Current electricity is a flow of electrons
  • Static electricity is a build-up of charges (+ or -)
a circuit
A. Circuit
  • Is a path of electron flow
    • Usually includes:
      • source (battery)
      • conductor (wire)
      • load (lamp or device)
      • switch (opens or closes a circuit)
    • Must be complete /closed for electricity to flow
sidenote
Sidenote:
  • Microcircuits –small circuits with low voltage and current.

Where have you seen these parts before?

slide24

Circuit symbols:

wire

lamp

switch

resistor

- +

Cell (battery)

a circuits
A. Circuits
  • Schematic diagrams – a neat representation of a circuit using circuit symbols
b terms of current electricity
B. Terms of Current Electricity
  • Conductors– materials which allow the flow of electrons (ex. Metals, water)
  • Insulators – materials which prevent (resist) the flow of electrons (ex. Plastic)
  • Load – a device which converts electrical energy to other forms of energy
    • Ex. Lamp, Radio, Motor
b terms of current electricity2
B. Terms of Current Electricity
  • Examples:

1. What is the difference between 1.0A and 3.0A?

2. What is the difference between 1.5V and 9.0V?

3. What is the difference between 2.0 and 6.0 ?

video
Video
  • How could the following picture be a metaphor for:
    • current
    • voltage
    • resistance
b modeling electricity
B. Modeling Electricity

Ex. Waterfalls

Current – how quickly the water is flowing down the waterfall

Resistance – how many rocks are in the stream bed, preventing the flow of water

Voltage – the height of the waterfall (how much energy the water has)

c cells and batteries
C. Cells and Batteries
  • Cells and batteries create current electricity in a circuit

>Create the electron flow

c cells and batteries1
C. Cells and Batteries

I. Basic Terms

  • Electrochemical Cell – a device that transforms chemical energy into electrical energy
    • Ex. AA, AAA – all 1.5V “batteries” are actually cells
i basic terms
I. Basic Terms
  • Batteries –multiple cells joined together to create a larger voltage
activity cell vs battery
ACTIVITY: Cell Vs. Battery
  • Predict the voltage of each of the following:

Remember: 1 cell = 1.5V

i basic terms1
I. Basic Terms

Dry cells – when the electrolyte is a paste

Wet cells- when the electrolyte is a solution

i basic terms2
I. Basic Terms

Primary cells – cells that cannot be recharged

Ex. Manganese-oxide alkaline batteries

Secondary cells – cells that can be recharged by using electrical energy to reverse the chemical reaction

  • “rechargables”

Ex. Car batteries, cell phones, Ni-Cd batteries

- will wear out over time

ii parts of an electrochemical cell
II. Parts of an electrochemical cell
  • 1 or 2 Electrolytes – a solution or paste that conducts electrolytes (ions)
  • 2 Electrodes – metals/ solids conductors (allow movement of e-)
    • Made of different metals
    • Cathode is positive (receives electrons)
    • Anode is negative (gives away “Source” of electrons)
slide39

III. How A Cell Works

1. Electrons are transferred from the negative electrode through a wire – head to the load

(+)

(-)

iii how a cell works
III. How A Cell Works

2. Ions (Ex. Cu2+(aq)) from the electrode are transferred through the solution (electrolyte) to the positive electrode.

3. The anode eventually is

“eaten away” or used up

(+)

(-)

slide41

Draw a Cell in Action!Draw a cell with the following parts: -copper electrode, copper solution -nickel electrode, nickel solution -wire -bulb -2 beakers

cell lab evaluating cell design
Cell Lab: Evaluating Cell Design
  • Summarize the following:
  • What affect does decreasing the concentration of an electrolyte have on the voltage of a cell?
  • What affect does using the same electrodes have on the voltage of a cell?
  • What affect does using different combinations of electrolytes have on the voltage of a cell?
iv applications of cells and batteries
IV. Applications of Cells and Batteries
  • We can apply batteries in useful ways:

Electrochemistry – the study of chemical reactions to produce electricity

  • Electrolysis – using a battery (electricity) to split a compound into its elements

Ex. H20 -->

iv applications of cells and batteries1
IV. Applications of Cells and Batteries

2) Electroplating – coating a metal with a thin layer of a wanted metal

  • The object to be plated is connected to the (-) negative electrode of the battery

Ex. Plating inexpensive jewelry with gold

iv applications of cells and batteries2
IV. Applications of Cells and Batteries

3) Galvanizing–coating parts with a layer of aluminum oxide (is much harder than aluminum)

Ex. Jewellery, screen doors, kitchenware

iv applications of cells and batteries3
IV. Applications of Cells and Batteries

4) Electrorefining–removing impurities from metals

-impure metals are placed at (+) electrode and a pure metal is placed at (-) terminal.