Electricity Unit Test

What is current electricity?

Current electricity is a controlled flow of electrons through a fixed path. 

The paths we use are called electrical circuits. 

What are the 4 parts of a complete circuit?

• Source

• Load

• Switch

• Wires

What is a switch in a circuit, what does it do in a circuit?

A switch opens and closes circuits and allows or blocks electrons from passing through.

What is a load/resistor, what does it do in a circuit?

Load/Resistor converts electrical energy to another form (light and heat).

What are wires, what do they do in the circuit?

Wires connect all parts of the circuit and allow electrons to pass through. 

What is the source, what does it do in a circuit?

The source provides the push that makes current move around the circuit. 

What does a voltmeter measure?

A voltmeter measures the potential difference across a source or load.

How is a voltmeter connected?

If you want to measure the voltage of the entire circuit, you connect the voltmeter to the source. However if you want to find the voltage of the load, you connect the voltmeter to the load.

Shortly: The voltmeter is connected in parallel with a part of a circuit.

What does an ammeter measure?

An ammeter measures the current passing through a circuit.

How is an ammeter connected?

You put an ammeter in line with the wires so it can measure the flow of electricity.

What is potential difference/voltage?

Voltage is how much energy electricity gains or loses as it moves through a source or a load.

What is the symbol of voltage/potential difference?

V

What is the unit of measurement for voltage/potential difference?

Volts

What is voltage measured by? Which device?

Voltmeter

What is current?

Current is the flow of charges through the wires where the current is always the same.

What is the symbol of current?

I

What is the unit of measurement in current?

Amperes

What is current measured by?

Ammeter

What is resistance?

Resistance is the flow of charges and how easy it is for them to move. 

High resistance- hard to move

Low resistance- easy to move

Resists the flow of current (high resistance)

What is the symbol of resistance?

R

What is the unit of measurement in resistance?

Ohmmeter

What is a series circuit?

A circuit where all components are connected one after the other in a single path and only have one path to flow. 

What is a parallel circuit?

A circuit where all components are connected in separate branches, so electricity has more than one path to flow.

What is voltage in series?

Voltage in series is when charges pass through a load (ex. light bulb) it loses energy.

• total voltage from the battery is split across all the components.

What is voltage in parallel?

Voltage in parallel is the voltage across the source and each of the loads is the same. (all values are the same). So if the source has a voltage of 12, then all the loads also have a voltage of 12. 

What is current in series?

The current in series is the same in every point because it follows the same path. So if in one spot the current is 9 amps, then that’s the speed of the current throughout the entire circuit.

What is current in parallel?

Current in parallel splits between different paths and separates the total current.  They continue down and into the next path. The different paths in the circuit don’t have the same current, but when added up they equal to the total current of the entire circuit. 

What is resistance in series?

Resistance in series adds all the individual resistors together. The loads don’t have to have the same resistance. 

Rt= R1 + R2 + R3

What is the resistance in parallel? (Optional)

The numbers that are the resistance of the loads change into reciprocals. Meaning if the resistance of one of the loads is 3, we would flip it and turn it into 1 over 3. 

1rt = 1r1 + 1r2 + 1r3

 change denominators and solve to find the total resistance of the entire circuit. .

What is ohm’s law?

Ohm’s law shows that voltage is how hard the electrons are pushed, current is how fast electricity is flowing, and resistance is how hard it is for electricity to move. 

Voltage → how strong the push is

Current → how fast electricity is moving

Resistance → how hard it is for electricity to move

What is practical building wiring?

Practical building wiring shows how electricity is safely installed in a practical way inside buildings.

What’s a circuit breaker?

Circuit breaker is a safety device that will prevent any circuit from carrying too much current and starting a fire. It has 2 strips of metal that bend when they get hot, causing the switch to open and stopping current from flowing.

What is a GFCI?

A GFCI outlet is used in places near water. If water gets on it, it could cause a shock, so the outlet quickly turns off the power when it senses a problem.

What’s a fuse?

A device that opens a circuit when there’s too much current so that the electrons can’t flow through. 

What’s grounding?

Grounding happens in a parallel circuit only. There's an extra wire in the circuit that takes extra current from the circuit through the wire into the ground whenever there is extra current that isn’t needed there. 

What’s a 3 hole outlet?

The third hole in an outlet connects to the metal parts of a device and sends electricity safely into the ground to prevent shocks.

What are some other safety tips?

• unplug devices when not in use

• keep wires in good shape, without cracks (cracks can cause shocks)

What’s a smart meter and how does it work?

A smart meter measures how much electricity you use and sends that information to the power company without someone coming to read it.

What’s time of use pricing?

The pricing is the highest during on-peak use (when the most electrical energy is used) and lowest during off-peak use (when the least electrical energy is used)

What are the Energize and Energy Star labels?

The EnerGuide label shows how much energy a machine uses. Buying a more efficient machine may cost more at first, but it saves money over time. A cheaper, less efficient machine costs more to run. The Energy Star label shows which machines are energy-efficient.

What is a phantom load?

A phantom load is when an electrical device is on even when it's turned off. The device is in stand by mode and is still using energy.

In order for the device to stop using energy, instead of turning it off, it’s better to unplug it. 

Ex. Even if the microwave isn’t warming up food, it’s still using up electricity to keep the clock and control panel going. 

What are some tips for saving energy at home?

• unplug devices

• look for energy star or energuide labels

• use during off-peak times

How is energy measured?

We measure energy in kilowatt/hours because joules/second are too small to be practical.

How do we find the cost of operating?

To calculate the cost of operating you use the formula:

cost to operate=power used x time x cost of electricity

Explain how energize labels are useful to consumers.

These labels help people compare products, choose ones that use less energy and cost less to run, and trust the information instead of ads.

How do power stations make electricity? Do they use renewable or nonrenewable resources? What are renewable and nonrenewable resources?

Power stations make electricity by using energy to spin turbines that turn generators, and they can use either renewable or nonrenewable resources.

How do we generate electricity in Ontario (name 3 ways)? What are some of the social, economic and environmental impacts of these methods? 

• Nuclear power

• Hydroelectric power

pros: provides thousands of jobs, renewable, benefits local economy

cons: destroys habitats, cause fragmentation, causes damage to water

• Thermoelectricity

List the pros and cons of series circuits in a house.

Pros:

• simple and cheap to build

• uses less wire

• can’t turn the devices off/on independently

Cons:

• voltage is split, so devices can’t get full power

• if one device breaks, everything turns off

List the pros and cons of having parallel circuits in a house.

Pros:

• each device gets the full voltage

• if one device breaks, others still work 

• devices can be turned on/off independently

Cons:

• uses more wire, which makes it cost more

• It can use a lot of electricity, so safety devices like breakers and fuses are needed to keep things safe