Module 4: Electricity

In electric circuits what is on the move?

In electric circuits electrons are on the move

Define electricity

Electricity is the flow of electrons through a conductor

What can the energy of the electrons be converted into?

The energy of the electrons can be converted into other forms of energy in devices such as light globes (light) and electric motors (kinetic)

What do electric circuits consist of?

• Power supply

• Load (or loads)

• A conducting path

What is the role of the power supply?

The power supply is the source of electricity

What is the role of the load (or loads)

They convert electricity to other forms of energy

What is the role of a conducting path?

It allows charge to flow around circuit

What is a conductor?

Conductors are materials that allow electrical current to flow through

What is an insulator?

Insulators are materials that do not allow electrical current to flow through them

When will electricity travel around a circuit?

Electricity will only travel around a circuit that is complete

What does it mean if a circuit is complete?

It means it has no gaps

A series circuits has:

A single loop/ no branches

What happens if you add more bulbs to a series?

It will reduce the electrical energy

How are different components connected in parallel circuits?

Different components are connected on different branches of the wire

In parallel circuits, will components connected on different branches keep working if components on another branch break?

Yes

What happens if you add more lamps to a parallel?

They stay bright

What happens if you add more batteries to a series circuit with bulbs?

It will increase the electrical energy and make the bulbs lighter

What is electric current measured in?

Electric current is measured in Amperes (A)

Electricity is measured using an…

Ammeter

To measure the current flowing through a component in a circuit, how must you connect the ammeter?

You must connect the ammeter in series with it

What is voltage?

Voltage is a measure of electrical energy carried by the charges in a circuit

What is voltage measured in?

Voltage is measured in Volts (V)

Voltage is measured using a…

Voltmeter

To measure the voltage (potential difference) across a component in a circuit how must you connect the voltmeter

You must connect the voltmeter in a parallel with it

What are conductors?

Conductors are materials that allow electrical current to flow through them

What are insulators?

Insulators are materials that do not allow electrical current to flow through them

What do materials which are able to conduct electricity have?

Materials which are able to conduct electricity have electrons which are free to move

What type of energy does the cell contain?

Chemical energy

What does the cell convert this energy into and why?

The cell converts this energy into electrical energy for electrons to collect

What do the electrons do with this electrical energy?

The electrons carry this electrical energy to the lamp where it is converted to light and heat energy. The electrons then continue around the circuit, back to the cell to collect more energy.

Will the electric current be the same at any point in the circuit? Why?

Yes, the electric current will be the same at any point in the circuit because the electrons are used up and all travel at the same speed

Is current used up by the components in a circuit?

No, current is not used up by the components in a circuit

What can moving electrons collide with in a metal/conductor?

ions

What does this make more difficult?

This makes it more difficult for the current to flow and causes resistance

What is electrical resistance?

Electrical resistance is a measure of how difficult it is for electrons to flow through a part of a circuit

What does resistance to the flow of electric charge limit?

Resistance to the flow of electric charge limits the size of an electric current

What does electrical resistance also determine?

Electrical resistance also determines how much energy is lost through transformation to heat, light, etc

How much resistance do conductors have?

Conductors have very little resistance

How much resistance do insulators have?

Insulators have very large electrical resistance

Give some examples of conductors:

• Silver, Gold, Copper, Steel and Sea water

Give some examples of insulators:

• Rubber, glass, oil, diamond, dry wood

What do resistors do in circuits?

In circuits, resistors make a precise quantity of resistance

What is the main function of resistors in a circuit?

The main function of resistors in a circuit is to control the flow of current to other components

What are three uses of resistors in a circuit?

• Adjustable lights

• Volume control on a radio

• Limit current through a charger

What does resistance do with increasing temperature?

Resistance decreases with increasing temperature

What does V stand for in the formulas for calculating resistance?

V = Voltage drop in volts → V

What does I stand for in the formulas for calculating resistance?

I= Electric current in amperes → A

What does R stand for in the formulas for calculating resistance?

R.= Resistance in Ohms → Ω

What is the formula used for calculating Resistance?

R = V    

       I

What is the formula for calculating the electric current?

I = V divided by R

What is the formula for finding the voltage

V = I x R

Name three energy sources that produce carbon emissions:

Coal, oil, natural gas

Name three energy sources that do not produce any carbon emissions:

Nuclear, wind, solar, geothermal, hydroelectricity, tidal

Name three energy sources that are not dependent on the weather:

Nuclear, hydroelectricity, coal, oil, natural gas, biomass

What is a force?

A force is a push, a pull or a twist

What is force measured in?

Force is measured in Newtons (N)

List all the forces:

• Applied force

• Gravity/weight 

• Friction

• Upthrust/buoyancy

• Air resistance/fluid friction/drag

• Normal reaction force

• Magnetic force

• Electrostatic force

• Driving force/thrust 

• Tension 

• Surface tension

What is energy?

Energy is the capacity for doing work

When is work done?

Work is done when force is applied to an object moves that object

What does energy transferred equal?

Energy transferred = work done

What are energy and work measured in?

Energy and work are measured in Joules (J)

List all the types of energy:

• Heat/thermal 

• Chemical

• Sound

• Light

• Elastic

• Kinetic

• Nuclear

• Electrical 

• Gravitational

What can energy not be?

Energy cannot be created or destroyed

Energy cannot be created or destroyed, it can only be…

Transferred from one object or one form to another

What do batteries provide?

Batteries provide a direct current (DC)

What does the constant voltage supplied cause?

A constant voltage supplied causes the current to flow in one direction

What is the current supplied to through power points called?

Alternating current (AC)

In Australia what does the current alternate with a frequency of?

The current alternates with a frequency of 50 Hz (50 times per second)

In Australia how does the voltage fluctuate?

In Australia, the voltage fluctuates from a positive to negative value with a voltage equivalent to 240 V

What is alternating current supplied by and why?

Alternating current is supplied by power stations because it is more efficient to distribute over large distances through the power grid

What is a transformer?

A transformer is an electrical device that changes the voltage of an alternating current (ac) supply

What is a transformer that increases the voltage called?

A step-up transformer

What is a transformer that decreases the voltage called?

A step-down transformer

At how many volts do power stations produce electricity?

Power stations produce electricity at 25,000 V

What are step-up transformers used to change the voltage to and what does it minimise ?

Step-up transformers are used to change the voltage 100 000 - 400 000 V which minimised energy lost but would be dangerous to use in homes

What are step down transformers used to do?

Step-down transformers are used to locally reduce the voltage to safe levels

What is the voltage of household electricity?

240V

If electricity companies transmitted electricity at 240 volts through overhead power lines why would there be too much power loss by the time electricity reaches our homes?

Because the current is too high

Why do transformers only work on AC?

Transformers only work on AC because alternating current in the primary coil causes a constantly alternating magnetic field. This will “induce” an alternating current in the secondary coil

What does it mean for an energy source to be non-renewable?

For an energy source to be non-renewable it means that they are finite natural resources, they form over millions of years, meaning they cannot be replenished quickly enough to keep pace with human consumption

What are the sources of electricity in Australia?

Black coal, brown coal, natural gas, hydro, wind, oil, bioenergy, solar power, other

Why are coal, oil and gas called fossil fuels?

Coal, oil and gas are called fossil fuels because they are made from the remains of living things that died millions of years ago

What is a greenhouse gas?

A greenhouse gas is a gas that traps heat in the Earth’s atmosphere

What are the positives of fossil fuels:

• Can power large cities

• Reliable

• Very cheap compared to alternatives

• Easy for countries to construct and manage

What are the negatives of fossil fuels:

• Non-renewable

• Produces soot/smog → Impacts health

• Carbon dioxide production → Impacts climate

Is Uranium a fossil fuel?

No

What are the positives of nuclear energy:

• Can power large cities

• Reliable

• Relatively cheap

• Enough to last thousands of years

What are the negatives of nuclear energy:

• Public perception

• Production of toxic waste

• Risk of meltdown

• Risk of terrorist attack

What is crude oil also known as?

Petroleum

What is crude oil (petroleum)

A thick black liquid that is separated into various products including petrol, diesel and kerosene

What are the positives of oil:

• High energy density 

• Easy to move 

• Simple to store

• Powers most transport

• Works in any weather

What are the negatives to oil:

• Produces carbon dioxide when burned

• Causes global climate change

• Refining creates toxic waste

• Releases smog and soot

• Causes acid rain from sulfur

What is natural gas?

Natural gas is a mixture of hydrocarbons and mainly contains the gases methane, ethane butane and propane

What are hydrocarbons

Hydrocarbons are chemicals made up of hydrogen and carbon atoms

What is a source of natural gas called?

A gas field

What is another way natural gas occurs?

With deposits of crude oil

What is the gas from rich deposits of methane gas inside coal beds called?

Coal Seam Gas (CSG) and is the purest form of natural gas

What are the positives of natural gas:

• Burns cleaner than coal or oil

• Releases less carbon dioxide

• Works on demand 

• Supplies abundant local fuel

What are the negatives of natural gas:

• Releases carbon dioxide when burned

• Leaks methane

• Poses explosion risks from gas leaks

• Can cause carbon monoxide poisoning

What are the two main qualities of renewable energy sources:

• Regenerate/replenish naturally

• Will last longer than the lifespan of the Earth