Topic 1.0: electrical energy, transferred/stored

Question 0

Atoms

Answer 0

The protons are in the nucleus and the electrons orbit the nucleus

Question 1

Proton/electron

Answer 1

P: Have a positive charge
E: have a negative charge
Charges on particles can cause either attractive or repulsive forces between the particles

Question 2

Neutral

Answer 2

When most objects have equal amounts if positive and negative charge, which makes them neutral
Some objects can have more of one type of particle than another

Question 3

Static electricity

Answer 3

Means not moving or stationary

It doesn’t flow like the electrons in an electrical current

Question 4

Charge separation

Answer 4

Caused by charged objects when they are brought close to neutral objects
Ex. Rubbing a balloon on your head transfers electrons from your hair to the balloon
When you bring the charges side of the balloon to a wall the negative charge of the balloon repels the electrons in the wall (opposites attract)

Question 5

Electrical discharge

Answer 5

The build up charge on an object may attract to another object and jump to that object
Ex. When your feet move across the carpet, electrons transfer from the carpet to your body. This excess charge of electrons in your body repels the electrons in the doorknob as you get close to it. The doorknob part that is closest to you is positively charges there for the negative electrons in your body moves to the knob and creates a shock

Question 6

The laws of electrical charges

Answer 6

Opposite charges attract each other

Like charges repel each other

Question 7

Van De Graaff Generators

Answer 7

Scientists use this device to study electrician discharge
They are effective for building up static charge using friction
A rubber belt rubs on a piece of metal and transfers the charge to a sphere. The charge builds up on the sphere and transfers I your body once you touch it

Question 8

Electrical current

Answer 8

The steady flow of charged particles
Is a type if electricity needed to operate electrical devices
Unlike static electricity because it flows continuously as long as two conditions are met… The flow of electrical current requires an energy source and the electrical current will not flow unless it has a complete path or circuit for the charged particles to flow through

Question 9

Amperes

Answer 9

The rate at which an electrical current flows is measures in amperes (A) also called amp for short
Named in honour of the French physicist, mathematician and philosopher Andre-Marie Ampere
Most devices around a home have a current less than 15 A

Question 10

Conductors

Answer 10

Allows electrical current to move through easily
It brings electricity from the place it was produced to the place it was needed
Conduction of electricity through wires aloes for the transfer of electrical energy from place to place

Question 11

Circuits

Answer 11

Paths that control the flow of electricity
The electrical circuits path that electricity flows along is made of solid metal wires
Circuits can also include gases, other fluids or other substances
Usually includes a conductor, an energy source and a load

Question 12

Load

Answer 12

A device to convert electrical energy to another from of energy
Used in circuits
Ex. Light bulb: converts electrical energy to light and heat

Question 13

Electrical energy

Answer 13

Energy carried by charged particles

Question 14

Voltage

Answer 14

The measure of how much electrical energy each charged particle carries
The higher the greater the potential energy of each particle
also called potential difference

Question 15

Potential difference

Answer 15

Another name for voltage

The energy delivered by a flow if charged particles is equal to the voltage times the total charge of electrons

Question 16

Volt

Answer 16

The unit of voltage (V)
Named after Italian physicist Alessandro Volta
For safety reasons most of the voyages in everyday devices are fairly low
Ex. Flashlights and partake stereos rarely use more than 6 V

Question 17

Measuring voltage with a voltmeter

Answer 17

The simplest way to measure voltage
Have sensitive needles that can be damaged if connected improperly
Attach red lead to positive terminal
Attach black lead to negative terminal
Some voltmeters have more than one red terminal: used to change the range of voltage readings on the voltmeter
If the meter is several ranges you may be unsure which one to choose… Start with the highest one and work your way down till you get a clear reading

Question 18

Millivolt

Answer 18

Some meters have readings in millivolts
Each is 1/1000 of a volt
Some meters have digital displays which make the voltage values very easy to read

Question 19

Measuring voltage with computers

Answer 19

Connect a voltmeter to a computer to measure voltage as well
With this device tho connect the terminals the same way as for other voltmeters but your voltage reading appears on a computer screen

Question 20

Short circuit

Answer 20

When the current inside the circuit bypasses part of the normal circuit
However if the electricity can find another path to flow through such as a persons body to the goring then it will take that path
Ex. When a power line gets knocked down all the power goes out because it has interrupted the circuit

Question 21

Dangers of electrical shock

Answer 21

Consider to important aspects if electricity: voltage and amperage
High voltage is dangerous compared to low voyage: however some small voltages can kill if the chock carries a significant number of amps
The number if amps is more important than voltage when assessing the potential danger of an electrical shock
Ex. If there were to jump or step out of a car that has been electrocuted the person would create a path for the electricity to travel through into the ground and harm the person… You should stay in the vehicle and wait for help

Question 22

Insulators

Answer 22

Affect electrical shock by making the current not flow easily
Ex. Wood, rubber and air
Substances such as mud or damp soil can conduct some electricity.. You might feel a shock by roughing a dry fence while wearing shoes but if you are bare foot and in the rain you would receive a terrible shock

Question 23

Protecting yourself from electrical shock

Answer 23

Never handle electrical devices while we for near water
Don’t use a power cord that is frayed/broken
Always unplug electrical devices before looking in or servicing them
Don’t out anything in an electrical outlet rather than proper plugs
Don’t over load circuits by plugging in too many devices
Stay away from power lines
Don’t bypass safety features on devices or in home
When unplugging device don’t pull on cord, on plug instead
Never remove the third prong on a three-prong plug

Question 24

Grounded three prong plug

Answer 24

Has an extra wire that connects to a device to the ground wire of the building
It provides another pathway for electricity just in case if there is a short circuit in the device

Question 25

Fuses/circuit breakers

Answer 25

Interrupt a circuit when too much current is flowing through it
Fuses contain a thin piece of metal that is designed to melt if too much current passes through
Circuit breakers have a special wire that heats up if there is too much current, instead of melting it turns off a switch inside and as soon as it cools the circuit can be turned back on( do not turn back on if the problem isn’t fixed)

Question 26

Danger of lightning

Answer 26

Lighting strikes have the potential to kill due to its high level of amps
Lightning is a huge amount of negative charge and tends to seek the highest point on the horizon to discharge
Avoid standing on high hilltops or under trees or holding objects above your head ( metal ones!) if you are in a thunderstorm
Lighting rods are added to tall buildings so the the lightning discharges on the rod and travels down a wire into the soil where it will not damage the building

Question 27

Pacemaker

Answer 27

Is inserted just under the skin near the shoulder and connected to the heart
An electrochemical cell supplies the electricity to keep the persons heart beating regularly

Question 28

Electrochemical cell

Answer 28

Supplies a steady current of electricity and is a package of chemicals designed to produce small amounts of electricity
The electricity that it produced comes from chemical reactions

Question 29

Two main types of cells

Answer 29

Dry cells and wet cells

Question 30

Dry cells

Answer 30

Used in every day flashlights and portable radios
Called “dry” because the chemicals are in a paste
They are also sealed so they can be used in any position without the chemicals leaking out
The chemical reaction in the cell releases free electrons
These electrons travel from the negative terminal of the cell, through the device and back to the positive terminal of the cell
It is made of two different metals in an electrolyte

Question 31

Electrolyte

Answer 31

Is a paste or liquid that conducts electricity because it contains chemicals that from ions

Question 32

Ions

Answer 32

Atom or group of atoms that has become electrically charged through the loss or gain of electrons from one atom to the other

Question 33

Electrodes

Answer 33

Electrolyte reacts with the two metals called electrodes
As a result of the reaction, one electrode becomes positively charged and the other negatively charged
These electrodes are connected to the cells terminals

Question 34

Alkaline cells

Answer 34

Become most common type of dry cell

Offer good combination of cost, electricity, output, shelf life, reliability and leak resistance

Question 35

Wet cells

Answer 35

Another type of electrochemical cell
They are wet and uses a liquid electrolyte that is usually an acid, such as sulfuric acid
These cells are used in cars and trucks today and in earlier cells they are cheaper and easier to make compared to dry cells
Care must be taken to not spill the liquid electrolyte which is highly corrosive
Ex. Each electrode in the wet cell reacts differently with the electrolyte. The acidic electrolyte gradually eats away the zinc electrode
This process leaves behind electrons that give the slowly disappearing electrode a negative charge
Eventually the zinc electrode must be replaced
The chemical reaction between the copper electrode and the acid ice electrolyte leaves the copper with a positive charge but doesn’t eat the copper away
Electrons travel along the wire from the negative zinc electrode to the positive copper lever rode.. You can connect a bulb with wires to make it light up by this cell
Car batteries are made of wet cells

Question 36

Primary cells

Answer 36

Dry cells and wet cells

Produce electricity from chemical reactions that cannot be reversed

Question 37

Rechargeable cell: secondary cells

Answer 37

The chemical reactions can be reversed compared to primary cells
Uses an external electrical source to run electricity back through the cell
The reversed flow of electrons restores the reactants that are used up when the cell produces electricity
Used it start cares and to operate portable electronic devices such as cellular phones
Must be reversed effectively through the reaction so hundreds of recharging cycles are possible

Question 38

Batteries

Answer 38

Connecting cells together creates a battery

Most are sealed into cases with only two terminals so many people don’t realize that they contain more than one cell

Question 39

Electrochemistry

Answer 39

Alessandro Volta made the first practical battery around 1800
He realized that connecting a lot of cells together could produce voltage and power
This innovated Humphry Davy from England to make a massive battery made if 2000 cells

Question 40

Electrolysis

Answer 40

Using smaller batteries to split molecules into their elements
Davy’s battery was so powerful that her could desperate pure metals from molten compounds and ores
He discovered potassium, sodium and other elements through electrolysis
Many industrial processes use electrolysis to separate useful elements from solutions
Electrolysis of water produces fuel for the space shuttle

Question 41

Electrochemistry

Answer 41

The study of chemical reactions involving electricity
Obtaining electricity from a chemical cell is just one of the many applications of electrochemistry… Electrolysis is another

Question 42

Electroplating

Answer 42

The process of making less expensive products by coating cheaper metal with a thin layer of silver or gold
The item must be coated and a bar of the coating metal are immersed in an electrolyte like the electrodes in a wet cell
The source of electricity is connected between the two metals
The flow of electricity through the electrolyte deposits atoms from the positively charged metal onto the negatively charged one
Is often used to protect metals from corrosion

Question 43

Other forms if electrochemical applications

Answer 43

Anodizing: coating aluminum parts with a thin layer of aluminum oxide, oxide coating is much harder and is used on a wide range if products
Electrorefining: used to remove impurities from metal
A current is applied an it moves from one electrode to the other… Ex. Pure gold than dissolves from the impure electrode to the other, eventually purifying it and uses it to produce very pure gold through electrolytes and electrodes