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ELECTRICITY - HANDOUT

ELECTRICITY BASICS

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ELECTRICITY - FARADAY

Faraday Basics

Faraday's law of induction is one of the important concepts of electricity. It looks at the way changing magnetic fields can cause current to flow in wires. Basically, it is a formula/concept that describes how potential difference (voltage difference) is created and how much is created. It's a huge concept to understand that the changing of a magnetic field can create voltage.

Faraday's Work

Michael Faraday was an English physicist working in the early 1800's. He worked with another scientist named Sir Humphrey Davy. Faraday's big discovery happened in 1831 when he found that when you change a magnetic field, you can create an electric current. He did a lot of other work with electricity such as making generators and experimenting with electrochemistry and electrolysis.

Faraday's experiments started with magnetic fields that stayed the same. That setup did not induce current. It was only when he started to change the magnetic fields that the current and voltage were induced (created). He discovered that the changes in the magnetic field and the size of the field were related to the amount of current created. Scientists also use the term magnetic flux. Magnetic flux is a value that is the strength of the magnetic field multiplied by the surface area of the device.

Faraday's Law

You're going to have to review your Greek letters when you memorize the real formula. Here are the basics...

E=dB/dt

"E" is the value of voltage induced (the old name for voltage was "ElectroMotive Force", or EMF. That's the "E" in the equation). The change in time for the experiment is "dt". Time is measured in seconds. Last is "dB" which stands for the change in magnetic flux. The magnetic flux is the field lines of the magnetic field. The flux is equal to BA, where B is the magnetic field strength, and A is the area. This formula is a bit harder than those you may have seen before.

In English: the amount of voltage created is equal to the change in magnetic flux divided by the change in time. The bigger the change you have in the magnetic field, the greater amount of voltage.

ELECTRICITY FACT SHEETS

ELECTRICITY FACTS

ELECTRICITY BOOK

• Read pages 8-11

ELECTRICITY - HOW TO MEASURE

Learn about Electricity:

Electricity is a very useful form of energy. 

Electricity can be used to perform work such as:

• Heating our homes or our food (electrical energy is converted into light and heat energy)
• Lighting our lamps (electrical energy is converted into light and heat energy)
• Powering our computers (electrical energy is converted into light, heat and sound energy) or
• Powering a motor (electrical energy is converted into movement, heat and sound energy).

 

  

But where do these items get their electricity?

All appliances, whether small or large, need a power source.

What is a power source?

A power source provides a steady flow of electrons. Larger appliances like heaters and large computers usually get their power from the mains. But small batteries (cells) can also be a power source.

The problem with electrical energy obtained from battery power though, is that battery power eventually runs out and the battery has to be thrown away or recharged. On the other hand, electricity flowing from a mains doesn’t run out is much more powerful (and dangerous so be careful!).

Electricity is a “secondary” source of energy. In other words other sources of energy are needed to produce electricity.

 

What is an electrical circuit?

Electrical current needs a PATH on which to travel. Another name for this path is a circuit.  Electricity flows from the power source, in a loop or a circuit, back to the power source. This means that the electricity must start and finish at the same power source. If the circuit is not complete (i.e. if the loop is not closed) then electricity cannot flow through it properly.

Which one of these loops allows electricity to flow?

LOOP1 or LOOP2?  

Explain your answer.

LOOP 1:

LOOP 2:

Electricity flowing through a circuit is called a current.

A load is a device that uses electricity (like a buzzer of a light blub). The load needs electrical energy to be able work.

The electric current from the power source flows from one place to another through the wire of a circuit.

Conductors and Insulators:

 These metal wires (conductors) are often wrapped in plastic (insulators) so as to stop the electric current flowing into objects that touch the wire.

If electricity flows through an object, then scientists say the object conducts electricity, and they call it a conductor. 

Metals are very good conductors. A small bit of energy is released as heat when electricity flows through the conductor.

If electricity doesn’t flow through an object then scientists call it an insulator. Plastic, wood and rubber are all very good insulators.

Here’s an experiment you can do at home to test if different materials are insulators or conductors.

You can increase a circuit by increasing the length of the connecting wire. What do you think will happen to the light bulb as the wire gets longer? How about as the wire gets shorter?

 

What is a switch?

 Switches allow you control over the circuit. You can stop the flow of electricity by breaking the circuit. When the switch is in the “on” position the circuit is complete. When the switch is “off” position the circuit is broken.

Here are some instructions to help you do some science at home and make your own switch.

 

How do I draw a circuit?

Sometimes circuits are drawn using special symbols. These symbols make it faster and easier to draw circuits and once you understand what the different symbols stand for, these diagrams are very easy to understand.  However if you don’t understand what the different symbols stand for, then the diagrams look a little strange!

Here is a chart to help you to understand the different circuit symbols that are used in when drawing the different components of the circuit. Each circuit component has it’s own symbol. These symbols are universal so we call all understand each other’s diagrams.

 

“In Series” or “In Parallel” Circuits:

Whenever two components are joined together in the same circuit, there are two different ways they can be wired: in series or in parallel.

In the in series circuit the components are joined together in one bigger circuit i.e. one continuous loop. 

Electricity passes first through one component first then the next one. 

A disadvantage of the in series circuit is that when one component malfunctions, the other components will stop working.

Another option would be to make two SMALLER circuits with each bulb having it’s OWN circuit parallel to one other. A major advantage of parallel circuits is that if one component malfunctions, the other continues to function.

The diagram below shows the difference between these two types of circuits.

Batteries can also be connected in parallel or in series. But, if you are using more than one battery in a circuit they need to all face in the same direction to work. If two batteries are connected in series, then the voltages add together.

Adding more cells in a line (in series) will make the blub burn brighter.

What do you think would happen if you add too many cells in the series?

ELECTRICITY - VIDEO

SIMPLE CIRCUIT - ACTIVITY

ELECTRICITY UNIT - VOCABULARY

ELECTRICITY - VOCAB TERMS & DEFINITIONS

Ampere - The ampere is the standard unit of measure of electric current. It is sometimes written as amp. 

Alternating current (AC) - An electric current that reverses direction on a periodic basis. It is widely used to transport power on power lines. 

Battery - A device that stores and produces electricity from chemical cells.  A battery has chemicals inside it. The battery is linked to a circuit. Then the chemicals inside the battery react together. This pushes a flow of electrons around the circuit.



Capacitor - A basic electrical component that stores electric charge. Capacitors are made from two electrical conductors separated by an insulator. 

Closed Circuit - circuit in which an electric current can flow from the power source to an object &  back to the power source in an unbroken pathsimple closed circuit

Conductivity - ability of an object to conduct or transmit heat, electricity, or sound


Conductor - material that can allow heat, light, sound, or electricity to pass through it easily.

• Example:  Metal is a good conductor of heat & electricity because it transmits them so easily (A material that allows the free flow of electric charge. Copper wiring is the most widely used electrical conductor.)

Coulomb's law - A law of physics that describes the electrostatic interaction between charged particles. 

Current electricity - the flow of electrons through a continuous path, or loop, from a power source & back to the power source. 

Diode - An electronic component that only allows current flow in one direction. 

Direct current (DC) - A type of current that only flows in one direction (unlike AC which periodically reverses direction). 
Dry cell battery - batteries that use paste-like chemicals to produce electricity

• Example:  used to power watches, toys, remote controls, portable radios, cell phones, calculators, flashlights

• some dry cell batteries can be recharged

Electric charge - This is a basic characteristic of matter that is based on the balance of protons (positive charge) and electrons (negative charge). The standard unit for electric charge is the coulomb. 

Electric circuit - An electric circuit is a collection of electronic components connected by a conductive wire that allows for electric current to flow. 

Electric current - Electric current is the flow of electric charge through a material. The standard unit for electric current is the ampere. 


Electricity - form of energy produced when electrons move, or flow, from one atom to another atom.  There are two types of electricity - static electricity & current electricity.


Electric potential - The electric potential is the difference in electrical charge between two points in a circuit. It is also called the voltage. The standard unit for electric potential is volts. 

Electromagnetism - The interaction between magnetic fields and electric currents. 

Electron - A basic subatomic particle found in all atoms, electrons carry electricity by flowing from one atom to the next in a conductive material. 

Insulator - A material in which electronic charge does not flow freely and does not conduct the flow of electric current, heat, light, or sound.

• Example:  Rubber is a good insulator for both electricity & heatIf one light bulb (or resistor) is turned off or breaks, the current will follow the other path.

Magnetic field - The magnetic influence produced by electric currents and magnetic materials. 

Ohm - The standard unit of measure for resistance. 

Ohm's law - A law of physics that describes the relationship between voltage, current, and resistance using the equation V = IR. 

Open Circuit - circuit in which an electric current cannot flow from the power source to an object & back to the power source
caused by a break in the circuit; switch is turned off & electric current is stopped at the switch                                                                     

Parallel Circuit - electric circuit that has more than one path for the current to follow.

In a parallel circuit, electricity can pass along different paths to power different loads.

Pole - the ends of a battery (positive pole & negative pole) & a magnets (north & south pole). 

Resistance - measure of how much a materiel slows down or stops electricity.  measured in ohms
Example:  Rubber has higher resistance so it is a poor conductor of electricity.  Copper has low resistance so it is a good conductor of electricity.
Calculating Resistance
Use the formula R = V/I

R = resistance (ohms)
V = voltage (volts)
I = current (amps)

Resistor - A basic electronic component that prevents the flow of electric current. 

Semiconductor - A material that behaves between a conductor and an insulator depending on the conditions. Silicon is a widely used semiconductor in electronics. 

Series Circuit - electric circuit that has only one path for the current to follow.  If one light bulb (or resistor) is turned off or breaks, the path is broken & the current will stop.

A series circuit has only one path of electricity. It provides power for more than one electrical load.

Static electricity - The build up of an electric charge on the surface of an object. The charge remains in one area rather than flowing to another area.  Rubbing together two objects made of different materials can produce static electricity.

• Example:  static electricity can be produce when a latex balloon is rubbed on a wool sweater.  Lightning 

Transformer - An electrical component that transfers electrical energy using inductive coupling between two winding circuits. 

Transistor - A semiconductor device used in an electric circuit to regulate current flow to act as a gate, switch, or amplifier for electronic signals. 

Volt - The standard unit of measure for electric potential (voltage). 

Voltage - Voltage is the name for the electric force that causes electrons to flow. It's the measure of potential difference between two points in the circuit. Voltage may come from a battery or a power plant.
Watt - The standard unit of measure used for electric power. 
Wet cell battery - batteries that use liquid chemicals to produce electricity 

• Example:  used in cars, trucks, & large construction equipment to provide power to start engines

They are usually about twice the size of a shoe box.

Wet-cell batteries contain lead and a solution of sulfuric acid.

Conductors and insulators - Conductors are materials that allow electricity to flow easily. Most types of metal are good conductors, which is why we use metal for electrical wire. Copperis a good conductor and isn't too expensive, so it's used a lot for the wiring in homes today. Insulators are the opposite of conductors. An insulator is a material that doesn't carry electricity. Insulators are important because they can protect us from electricity. Materials like rubber, plastic, and paper are good insulators.
ELECTRIC VOCAB TERM - ACTIVITY

ROAD SALT

VIRTUAL DENSITY LAB

COMPLETE THE DENSITY LAB -
PUT YOUR SCORE ON NOTEBOOK PAPER & PLACE IN DRAWER

SCIENTIFIC METHOD GLOSSARY

SCIENTIFIC METHOD GLOSSARY

Term	Definition
Conclusion	The solution or answer to a problem. The conclusion is what the scientist has learned about the problem through experimentation.
Controlled variable	A variable that must remain the same in all situations. Controlled variables are all of the things in an experiment that must remain the same.
Data	Pieces of information that a scientist will gather and look at. Data consists of information collected through research, experiments, and observations. Conclusions can be made based on data.
Data table	A T-shaped diagram that displays raw data from an experiment. It includes a manipulated and responding variable.
Experiment	A test or trial used to gain knowledge or to test a theory.
Graph	A diagram consisting of lines, bars, or circles to represent information. Science fair experiments usually require line graphs.
Hypothesis	A reasonable or educated guess. It is what a scientist thinks will happen in an experiment. Hypotheses are based on observations, research, and what is already known about the subject.
Log book	A notebook in which a scientist writes all of his or her notes about the experiment. All students who complete a science fair project must have a log book.
Manipulated variable	A variable that is deliberately or intentionally changed by the scientist in an experiment.
Metric measurement	A system of measurement that scientists use. Length is measured in meters, weight is measured in grams, volume is measured in liters, and temperature is measured in degrees Celsius.
Observation	The use of the five senses (seeing, hearing, smelling, tasting, or touching) to collect information.
Operational definition	The way a scientist measures variables. The operational definition explains specifically how each variable will be measured (hours, degrees, meters, liters, grams, decibels, etc.)
Ordered pairs	Number data that shows a relationship between the manipulated and responding variables. For example, if you gave a plant 10 ml of water each day, and the plant grew a total of 15 cm, then the ordered pair would be (10, 15).
Problem	Something that needs to be solved. Problems are usually questions that scientists ask about science topics.
Procedures	A methodical, logical way of doing something. Procedures include directions or plans, listed step by step.
Qualitative data	Sensory (sight, touch, smell, hearing, taste) information that is used to draw conclusions.
Quantitative data	Numerical (number) information that is used to draw conclusions.
Raw data	The initial quantitative information that a scientist gets while conducting an experiment. All raw data is written in a data table in the scientist's log book.
Responding variable	A variable that changes as a result of the manipulation of another variable. The responding variable is not changed intentionally, rather, it changes because of what the scientist changed intentionally.
Scientific Method	A logical way of solving problems. Scientists use this method to gather and test information. There are seven steps to the scientific method: Identify a problem Create a hypothesis Design an experiment Conduct the experiment Collect data Graph data Draw conclusions
Variable	Something that can change or "vary" in a situation.
X axis	The horizontal line at the bottom of a graph. The manipulated variable is always written on the x axis of a graph.
Y axis	The vertical line on the left side of a graph. The responding variable is always written on the y axis of a graph.