Science 7, 8 and 9

If your family used 3200 kW.h of electrical energy last month and the power company charges $0.09 per kW.h, calculate your last month's electric bill.

$0.09/kW.h X 3200kW.h = $288.00

Draw and properly label a sample of a circuit diagram.

(BE ABLE TO DRAW A CIRCUIT DIAGRAM)

Know the 7 circuit symbols on Figure 8.10.

(be able to draw them)

Know the 4 criteria in making circuit diagrams.

-Draw your diagrams using a ruler. -Make all connecting wires and leads straight lines with 90o (right-angle) corners. -If possible, do not let conductors cross over one another. -Your finished drawing should be rectangular or square.

It takes the addition or removal of electrons to produce 1C of charge.

6.25 X 10 (to the power of 18)

How many terminals does a battery have?

A battery has 2 terminals located at the end points where we make a connection. One terminal has more electrons than the other, making one negatively charged and the other positively charged.

1. What are electrochemical cells or batteries?

A battery is combination of electrochemical cells connected together, or single electrochemical cell that produces a potential difference. A battery provides a steady controlled flow of electricity.

Series circuit

A circuit that has only one path for current to travel.(current stays the same)

battery

A combination of electrochemical cells connected together, or single electrochemical cells that produces a potential difference.

electric circuit

A complete pathway that allows electrons to flow

ohmmeter

A device that measures resistance.

Van de Graaff generator

A device that uses friction to produce a large static charge on a metal dome.

ammeter

A device used to measure current in a circuit.

What is the relationship between the current entering and leaving a junction point?

A junction point is the place where the pathways separate or join. The current is not created or joined in a parallel circuit, it is simply split up to travel different routes. The total current entering a junction point must equal the sum of the current leaving the junction point.

What is a larger unit for electrical energy?

A larger unit for electrical energy is Kilowatts used for power. And time is measured in hours.

Power rating

A measurement of how much electrical energy an electrical device consumes for every second it is in use.

What is a power rating? Describe it in terms of a 1500 W hair dryer.

A power rating is a measure of how much electrical energy an electrical device consumes every second it is in use. In other words, 1.0 W is the transfer of 1.0 J of energy every second. This means a 1500 W hair dryer uses 1500 J of electrical energy each second.

Electric force

A push or pull between charged objects.

Force

A push or pull on an object.

In terms of power and the rate at which energy is transformed, explain why a sports car will reach the top of a hill faster than an old rusty car when they both have the same mass?

A sports car will reach the top of the hill faster than an old rusty car even though the have the same mass because the race car has a load that can transform the energy more quickly than the old rusty car. Therefore the race car will get there first. (batteries pushing the charge uphill)

What are superconductors?

A substance capable of becoming superconducting at sufficiently low temperatures.

Acetate

A type of plastic used in photographic film and overhead transparencies.

What happens to the electron after that?

After that it starts its journey all over again and gains potential energy back.

In order to charge an atom or material, what subatomic particle is transferred?

All solid materials are charged by the transfer of electrons. When an electron is transferred the charge changes.

Who invented the Van de Graaf generator? What is it used for?

American physicist Robert Van de Graaff. It it used to generate static charge.

Static charge

An electric charge that can be collected and held very nearly fixed in one place.

resistor

An electrical component with a set amount of resistance that slows down current and transforms electrical energy into other forms of energy

voltage

An electromotive force or potential difference expressed in volts.

Free electrons

An electron without a conducting substance.

What makes an atom or solid material neutral?

An equal number of protons and electrons makes a solid material neutral.

What is a electroscope?

An instrument for detecting and measuring electricity, especially as an indication of the ionization of air by radioactivity.

What is another equation for power? Compare it to the units used for each variable and be able to state what a watt is equal to in terms of joules and seconds. You should notice a pattern with your answer to 2 c.

Another equation for power is P = E/t

What is another name for static charge?

Another name for static charge is electric charge.

Define electric load and give 5 examples.

Any device that transforms electrical energy into other forms of energy is called an electric load. Some examples of a load are: Light bulb, a buzzer, a heater, and a motor and a T.V.

electric load

Any device that transforms electrical energy into other forms of energy, such as a light bulb, buzzer, heater, and motor

Compare the movement of electrons in a closed circuit to that of water in a hose connected to a tap.

As soon as the battery is connected to the circuit, and the circuit is closed, electrons in every part of the circuit are pushing. That is why the light bulb goes on immediately. If the hose is already filled with water, as soon as you turn on the tap, water flows from the other end of the hose. The electrons leaving the negative terminal push the electrons ahead of them, just like water leaving the tap pushes on the water in front.

battery terminals

Battery terminals are the electrical contacts used to connect a load or charger to a single cell or multiple-cell battery.

Why did Benjamin Franklin think that electricity flows from positive to negative?

Benjamin Franklin thought that electricity flows from positive to negative because he thought that the positive objects obtained more electric fluid than the negatively charged objects.

Compare a simple waterslide to that of a series circuit.

Charges with one path to follow. People are electrons as they travel up the stairs and then down the slide. If a person stops on either the stairs or the slide the rest of the people have to stop because that person is blocking the only path way to travel on. The series circuit only has one path to travel on.

Differentiate charging by conduction from charging by induction.

Charging by conduction is the process of transferring charge between objects by touching or rubbing. Charging by induction is the process of rearranging electrons on a neutral object by bringing a charged object close to it.

Describe Charles Coulomb's observations regarding the relationships between: a). the amount of charge and the electric force.

Charles Coulomb observed that electric force is proportional to charge. If you increase the amount of charge, you increase the electric force. Likewise if you decrease the amount of charge, you decrease the electric force.

Why are circuit diagrams important?

Circuit diagrams are important because circuit diagrams give an organized representation of the actual circuit

Grounding

Connecting a conductor so the electric charge flows into earth's surface.

a). Differentiate contact forces from action-at-a distance force.

Contact forces are forces that can have an effect only on objects they touch. Action-at-a distance force can apply force to an object without touching it.

b). Give an example of each.

Contact forces: Shooting a basketball, or friction, or pulling a desk across the ground. Action-at-a distance force: Bringing a charged comb near small pieces of paper, without making contact the paper will be attracted to the comb.

conventional current

Conventional current or simply current, behaves as if positive charge carriers cause current flow.Conventional current flows from the positive terminal to the negative terminal.

Conductors such as and allow charge to flow.

Copper and Aluminum

The unit of electric charge is . It's symbol is . It was named after French physicist .

Coulomb C Charles Augustin de Coulomb

Describe Charles Coulomb's observations regarding the relationships between: b). the distance between charged objects and the electric force.

Coulomb also observed that if you increase the distance between charged objects, you decrease the electric force. If you decrease the distance between charged objects, you increase the electric force.

Differentiate between decorative lights that won't work if one bulb burns out and other decorative lights and lights in your house that will work if one bulb goes out. How are they connected?

Decorative lights are different from the light bulbs we use to light the rooms of our homes. They are smaller and less bright. Another difference can be the way they are connected together. The decorative lights and the house lights are on two different circuits.

What can happen to electrons during friction?

During friction, electrons move around, one object will gain electrons, while the other will lose electrons.

What happens to the potential energy of the electron as it travels through a load?

Each load in the series circuit loses a portion of the total voltage supplied to the electrons by the battery. The sum of the voltages lost on the loads equals the total voltage supplied by the battery. As it travels through the load it loses all of it's potential energy before the electron comes back to where it started.

Why is electric force considered an action-at-a distance force?

Electric force is considered an action-at-a distance force because an electric force is a push or pull between charged objects, so it is not being touched.

What is electrical power? Describe what it is in terms of a "60 W" in a light bulb.

Electrical power is the rate of change in electrical energy. For example a 60W light bulb converts 60 J of electrical energy into 60 J of light and heat every second.

What are electrical surges and how are they caused? What is used to help protect electronic devices against this?

Electrical surges are brief increases in voltage to tens of thousands of volts. They can be caused by lightning, or turning on or off large electrical appliances, or by the power company transferring large amounts of energy into or out of the power grid. An electrical surge protector absorbs some of the electrical surge and then diverts the rest of it to the ground.

Electrical surges

Electrical surges can be caused by lightning, by turning on or off large electrical appliances. An electrical surge protector absorbs some of the electrical surge and then diverts the rest to the ground

What are electrodes made up of?

Electrodes are made up of two different metals but can be a metal and another material.

electrochemical cells

Electrodes in electrolytes that convert chemical energy into electrical energy stored in charges; also called batteries

kinetic energy

Energy a moving object has because of its motion; depends on mass and speed of object and the temperature

Explain why the energy in a battery is called electric potential energy?

Energy in a battery is called electric potential energy because the electrons have a stored energy and the ability to do work after they leave the battery.

Briefly describe five other sources of electrical energy.

Five other sources of electrical energy are Friction rubbing 2 materials together, piezoelectric crystals (a barbecue lighter), Photo electrochemical cells (solar panels, or calculators), Thermocouples (transforms heat energy into electrical energy), and Generators (electricity that enters most of our homes is produced by a generator.)

What is a force?

Force is a push or pull on an object.

Action-at-a-distance forces

Forces that can have an effect on objects without touching it.

Contact forces

Forces that have an effect only on things that they touch.

What did Georg Ohm realize when he studied the relationship between voltage and current?

Georg Ohm realized that voltage is directly proportional to current, he also realized that there is another factor involved.

An insulator is a material that does not allow electric charges to move easily. List 4 examples.

Glass Ceramics Plastics Dry wood

circuit diagrams

Graphical representation of an electric circuit.

What is grounding? When is it used?

Grounding is when you allow charge to flow into earth's surface. It is used in the Van de Graaf generator. Grounding is getting rid of all the charge an object has.

In a cell or battery, what does the chemical energy do?

In a battery, chemical energy separates the positive and negative charges.

Compare the pathways of the electrons in a series and parallel circuits.

In both circuits the electrons both travel in the same direction but in the parallel circuit they have more than one pathway to travel on and in the series circuit they only have one pathway to travel on.

electric potential energy

Is a potential energy(measured in joules) that results from conservative Coulomb forces and is associated with the configuration of a particular set of point charges within a defined system.

What happens to the electron's electric potential energy when it reaches the electric load?

It 'loses' all of its potential energy

How does induction explain why neutral objects are attracted to charged objects?

It is thought that when a negatively charged object gets close to an uncharged object, electrons in the uncharged object are repelled, leaving the positive charges behind. These positive charges are then attracted to the negatively charged object.

Differentiate kinetic energy from potential energy.

Kinetic energy is energy a moving object has because of it's motion. Potential energy is the energy stored in an object. The electrical energy stored in a battery is called electric potential energy.

What are lightning rods used for?

Lightning rods are used to protect a building from lightning. If lightning occurs near the building, the large amount of charge will pass through the lightning rod to the ground, rather than to the building.

Insulators

Materials such as glass, plastic, ceramics and wood that do not allow electrons to move freely on and through them.

Conductors

Materials that allow electrons to move freely on and through them.

A conductor is a material that allows electrons to move more easily. Give an example.

Metals People

Describe the 2 methods use to determine resistance.

Method 1: To experimentally measure the resistance of a device or load, the load must be connected to a source of potential difference, such as a battery. You can use a voltmeter to measure the voltage across the load and an ammeter to measure the current through the load. Then you can use Ohm's law to calculate the resistance. Method 2: You can use a multimeter. Most multimeters also have a setting for measuring resistance. An ohmmeter is a device that measures resistance. When a multimeter is used as an ohmmeter, the meter uses its internal battery to provide a voltage across the load.

Electron

Negatively charged particles surrounding the atomic nucleus.

What is Ohm's Law in equation form? Be able to solve for each variable (R=?, V=?, I=?).

Ohm's law in equation form is R = V/I

What are the charges of these terminals?

One is negative, one is positive.

Watt

One joule of energy transformed in one second, named in honour of Scottish inventor James Watt

Friction

One surface or object rubbing against each other.

List 5 uses of static electricity.

Plastic sandwich wrap Decrease air pollution Devices in chimneys Air ionizers-freshen homes Painting automobiles

Proton

Positively charged particle in the atomic nucleus.

What are the three ways to define power?

Power is defined as the rate of change in energy. Power is also the rate at which work is done. Also at which energy is transformed.

Charging by induction

Process of rearranging electrons on a neutral object by bringing a charged object close to it.

Charging by conduction

Process of transferring charge between objects by touching or rubbing.

List the 3 subatomic particles and their charges. Where is each located in an atom?

Protons are positively charged, they are located in the nucleus. Neutrons are neutrally charged and are located in the nucleus. Electrons are negatively charged and are located outside the nucleus circling it.

Explain why resistors are colour coded.

Resistors are color coded to indicate the resistance of the resistor.

What is the importance of a resistor in a circuit?

Resistors are important in a circuit because they can be used to control current or potential difference in a circuit to provide correct voltage.

In early studies of static electricity, scientists hypothesized that there were two"electricities". Why? (p. 249)

Scientists observed that rubbing materials such as amber produces one kind of electricity and rubbing materials such as glass produces a different kind of electricity.

Describe the movement of electrons in a battery.

Since there is a pathway for them to travel, electrons leave the negative terminal and are pushed by the energy from the battery through the conducting wires to the buzzer. In the buzzer, the electron's' electric potential energy is transformed into sound energy. Electrons travel back to the battery through the complete circuit.

How are solid materials charged?

Solid materials are charged by friction.

Describe the 4 basic components of a circuit.

Source: the source of electrical energy Conductor: the wire through which electric current flows Load: a device that transforms electrical energy into other forms of energy Switch: a device that can turn the circuit on or off by closing or opening the circuit.

electrolyte

Substance that conducts an electric current. In a dry cell, the electrolyte is a moist paste; in a wet cell, the electrolyte is a fluid.

List the 3 laws of static charge.

The 3 laws of static charge are: Like charges repel Opposite charges attract Neutral objects are attracted to charged objects

Who hypothesized that there was only one kind of "electrical fluid"? What did he use the terms positive and negative to describe? How is this different than how scientists today use positive and negative to describe electrical charge?

The American scientist statesman and inventor Benjamin Franklin hypothesized that there was only one kind of "electrical fluid". He called the buildup of electrical fluid positive and the shortage of electrical fluid negative. Scientists still use positive and negative to refer to the electrical charge on an object but now we have developed theories about electricity based on particles.

energy

The ability to do work

electric current

The amount of charge passing a point in a conductor every second

What are the 2 factors that potential energy of a battery depend on?

The amount of potential energy a battery can output depends not only on how much voltage the battery has but also on how much charge that battery can separate.

Compare the potential energy of an electron as it leaves the battery to when it returns.

The battery supplies the electrons with electric potential energy. If the battery has a potential difference of 12V, then the electrons will lose these 12V of potential difference by the time they return to the battery.

Differentiate static electricity from current electricity.

The continuous flow of charge in a complete circuit is called current electricity. Static electricity a stationary electric charge, typically produced by friction, that causes sparks or crackling or the attraction of dust or hair.

current electricity

The continuous flow of charge in a complete circuit.

What is the relationship between the current in each part of a parallel circuit? WHY?

The current is different. The sum of the current on each pathway adds up to the total current supplied by the battery. In a parallel circuit the current changes.

What is the relationship between the current in each part of a series circuit. WHY?

The current on the other hand is different from the voltage. Current measured anywhere in the series circuit will be the exact same everywhere.

What is the difference between Franklin's conventional current and the idea that we use today (flow of electrons)?

The difference is that his idea is opposite to our own. We use the idea today that it flows from negative to positive rather than positive to negative.

volt

The difference of potential that would drive one ampere of current against one ohm resistance.

voltmeter

The difference of potential that would drive one ampere of current against one ohm resistance.

Differentiate wet cells from dry cells.

The dry cells electrolyte is more of a moist paste, while the wet cells electrolyte is a liquid. Dry cells are used in flashlights, portable CD players and watches. Wet cells are commonly used in cars, motorcycles and electric wheelchairs.

Explain how a battery works.

The electrolyte is a chemical medium that allows the flow of electrical charge between the cathode and anode. When a device is connected to a battery—a light bulb or an electric circuit—chemical reactions occur on the electrodes that create a flow of electrical energy to the device.

What is the equation for electrical energy? Compare it to the units used for each variable and be able to state what a joule is equal to in terms of watts and seconds.

The equation for electrical energy is E = P x t P standing for power. E being energy travelled. And t being per time interval. Energy = power multiplied by time. E = Joules P = Watts. Joule is 1 coulomb per second.

What is the equation for electrical power? Be able to rearrange it to solve for each variable.

The equation for electrical power is P = VI. P being the electrical power. V being the voltage. And I being the current.

What does the filament of a light bulb do to the flow of electrons?

The filament of the light bulb resists the flow of electrons and therefore slows down the current.

Junction point

The location where a circuit divides into multiple paths or where multiple paths combine.

Ohm's Law

The mathematical relationship comparing voltage current and resistance written as R = VxI

lightning

The occurrence of a natural electrical discharge of very short duration and high voltage between a cloud and the ground or within a cloud, accompanied by a bright flash and typically also thunder.

What is the relationship between the voltages in each part of a parallel circuit? WHY?

The parallel circuit is opposite of the series circuit. The voltage is the same throughout each pathway. There are more than one pathway in the parallel circuit and the voltage is the same throughout each.

Describe how does the power company keep track of your electric consumption?

The power company keeps track of our electric consumption because your home probably has a meter that monitors your energy consumption. Every time you turn on a load, such as a light bulb, current passes through the meter and turns the dials. An employee of the power company visits your home and reads this meter to determine how much energy has been consumed since the last bill.

resistance

The property of any material that slows down the flow of electrons and converts electrical energy into other forms of energy

Electrical power

The rate of change in electrical energy.

Power

The rate of change in energy; also the rate at which work is done or energy is transformed.

electrical resistance

The ratio of voltage to current.

What is the relationship between voltage (of a source) and current?

The relationship between voltage and current is that when you increase the voltage the current will also increase. Therefore voltage and current are directly proportional.

What is the relationship between the voltages in each part of a series circuit? WHY?

The relationship between voltages is the sum of the voltage lost on the loads equals the total voltage supplied by the battery.

What is the relationship between voltage (of a load) and current?

The relationship is indirectly proportional because if you increase the voltage lost in the load the current will decrease.

Compare the resistance of a circuit to a grocery checkout.

The resistance in a series circuit compares because imagine that there is one checkout open, all the people must use this one checkout. This is like a series circuit because there is only one path. In this case the cashier is a resistor since the cashier slows down the customers. If another checkout is open customers can now use either line even though the cashier is also a resistor the customers do not have to wait as long. When you place a resistor in parallel with another resistor, you create another pathway so the total resistance must decrease. Resistors placed in parallel will decrease the total resistance of the circuit. When the total resistance of the circuit decreases, the total current leaving the battery must therefore increase.

Atom

The smallest particle of an element that retains the properties of that element.

What are the 3 kinds of charges?

The three kinds of charges are: Positive negative neutral

Neutral

The uncharged state of a particle or an object; occurs when the positive charge in the nucleus is exactly balanced by the negative charge of the electrons.

What is the unit used for measuring energy?

The unit for measuring energy is called Joule. Named after James Prescott Joule.

Joule

The unit for measuring energy, named for the English scientist James Prescott Joule.

Coulomb

The unit of electric charge named after the french physicist.

What is the unit used for measuring power? How is this unit also represented as a rate (using the unit for energy/time)?

The unit used for measuring power is called Watt. Equal to one joule of energy transformed in one second.

List 3 ways that you can do to reduce your monthly bill.

Three ways to reduce your monthly bill are don't use electricity when you don't really need it, aka turn it off when you're not really using it, Or you can go solar, or cut your AC/heating needs.

electrodes

Two terminals in a battery or other electricity source; usually made of two different metals but can be a metal and another material

amperes

Unit for measuring electric current; very small currents are measured in milliamperes.

ohm

Unit for measuring electrical resistance.

Parallel circuit

Voltage stays the same. A closed loop that has several paths for current to travel.

Why do we need a larger unit?

We need a larger unit because sometimes we have to deal with larger quantities of energy.

Briefly describe what happens when a CD or other electronic device is connected to the terminals.

When a battery is connected to a CD player, electrons can travel through the wires and into the player. The electrons stored electrical energy is transformed into sound energy.

Describe what happens to a neutral electroscope when a negative or a positive object is put in contact with it.

When a negative object is touched to a neutral electroscope, electrons are added to the electroscope. These electrons spread evenly over the entire metal surface of the electroscope leaves. The same thing would happen if the object was positive. Electrons from the metal the electroscope would be attracted to the positive object.

What does it mean when we say that energy is "lost" in a resistor?

When we say that energy is "lost" in a resistor, we really mean that electrical energy has been transformed to other forms of energy.

What happens to the resistance and current throughout the circuit when resistors are added in series?

When you add a resistor to a series circuit, all of the electrons slow down because if one slows down then they all slow down.

Briefly compare potential energy and potential difference with climbing a staircase.

When you climb a flight of stairs, your body has done work. The work you have done is now potential energy. If you had climbed the same set of stairs with a heavy backpack, you would have done more work. As a result, you and the backpack would have more potential energy. The potential energy thus depends on the height of the stairs and the amount of mass moved to the top. You can think of the potential difference in a battery as being like the height of the stairs.

What is the overall charge when an atom has b). more electrons than protons?

Will result in a negative charged atom.

What is the overall charge when an atom has a). more protons than electrons?

Will result in a positive charged atom.

Do electrons need to touch other electrons in order to push them? WHY?

Yes they do. In order for the light bulb to turn on immediately the electrons in every part of the circuit are pushing from the negative terminal to the positive terminal.

Horsepower

a unit of power equal to 550 foot-pounds per second (745.7 watts).

Convert the following:

a). 36 mA = 0.036 A b). 3.2 kΩ = 32000 Ω c). 15 MV = ____________ kV = 15 000 000 V

Since static electricity is held in one place, only....can retain static electricity.

insulators

When a material gains electrons, it is....

negatively charged.

When a material loses electrons, it is....

positively charged.

potential difference

the amount of electric potential energy per one coulomb of charge at one point in a circuit compared to the potential energy per coulomb of charge at another point in the circuit; also called voltage

potential energy

the energy possessed by a body by virtue of its position relative to others, stresses within itself, electric charge, and other factors.