S8P5 [details] Students will recognize characteristics of gravity, electricity, and magnetism as major kinds of forces acting in nature.

Element: S8P5.b Demonstrate the advantages and disadvantages of series and parallel circuits and how they transfer energy. Element: S8P5.c Investigate and explain that electric currents and magnets can exert force on each other.

Essential Question What is the role of electricity in our life?

You and your shoulder partner should complete the Path Finders Activity.

Is electricity flowing through the systems that make the bulb light Is electricity flowing through the systems that make the bulb light? How do you know? Is electricity flowing through the systems that don’t make the bulb light? How do you know? 1. What are similarities of the systems that work? 2. What are similarities of the systems that don’t work?

5. What do you think are necessary elements of all complete circuits?

What is the difference between static electricity and current electricity?

What is the difference between static electricity and current electricity? Static electricity is stationary or collects on the surface of an object, whereas current electricity is flowing very rapidly through a conductor.

Current Electricity Electric forces arise from the presence of an unbalance in electric charge. Electric Current is the flow of electric charges. Electricity always flows from a negative pole (excess electrons) to a positive pole (deficient in electrons).

Flow of Electricity a) The flow of electricity in current electricity has electrical pressure or voltage. (Push or pull from electric force) Electric charges flow from an area of high voltage to an area of low voltage. See point #3 under Current Electricity c) Electricity can only flow when there is a closed pathway for the charge to flow through

Let’s Pause to consider…

How is the flow of electricity similar to the movement of thermal energy?

Matter Classification Conductors Materials that allow electric charges to easily move through them. Examples: Metals Insulators Materials that do not allow electric charge to easily move through them. Examples: Nonmetals, glass

How is the flow of electricity similar to the movement of thermal energy? Thermal energy flow from high concentration (warm) to low concentration (cool) until equilibrium is reached. Electricity flows from high concentration (extra negative electrons) to areas of low concentration (deficient of electrons = positive area). Both flow from “high to low”.

Compare and contrast unbalanced forces that cause motion to the unbalanced forces that cause electric forces?

Compare and contrast unbalanced forces that cause motion to the unbalanced forces that cause electric forces? Unbalanced forces are required to cause a change in motion (acceleration or deceleration). Unbalanced electric forces are required to make electrons change their motion and move. Both require an unbalance (in force or electric charge) for something to happen.

Compare the flow of electricity to the flow of water

Electric Circuits How is the flow of electricity similar to the flow of water through a pipe?

How is the flow of electricity similar to the flow Electric Circuits How is the flow of electricity similar to the flow of water through a pipe? Both require a closed path or pipe. Water pressure and voltage are similar because the water or electricity flow from high pressure to low pressure

The pressure of the water flowing through the pipes on the last slide compare to the voltage (electric potential) flowing through the wires of the circuit. The unit used to measure voltage is volts (V). End for day 1

Water pressure and voltage behave in similar ways. What makes the water flow in figure A? Apply this answer to figure B using negative charges instead of water. Water pressure and voltage behave in similar ways. 23

Circuit Terminology Circuit uninterrupted pathway or loop through which electricity can flow (usually wire pathway)

Circuit Terminology Electric Current (I) Rate at which charges pass a given point; measured in amperes or amps (A)

Circuit Terminology Voltage (V) Potential difference between two points in a circuit; measured in volts (V)

Circuit Terminology Resistance( R) opposition to the amount of current in a wire "electric friction"; measured in ohms(Ω) ; depends on: a) Type of material b) Thickness and length of wire c) Temperature

What is electrical resistance? Resistance (R)is the opposition to the flow of an electric current, causing the electrical energy to be converted to thermal energy or light. The metal which makes up a light bulb filament or stovetop eye has a high electrical resistance. This causes light and heat to be given off.

The unit for measuring resistance is the ohm (Ω).

Ohm’s Law  

Alternating Current (AC) Two Types of Current Direct Current (DC) - charges always flow in the same direction - charges continually shift from flowing in one direction to flowing in the reverse direction Alternating Current (AC) 32

Generating DC Electricity Cell or Battery - device produces electric current by converting chemical or radiant energy into electrical energy Thermocouple - device produces electric current by converting thermal energy into electrical energy Photocells - device produces electric current by converting light energy into electrical energy 34

Parts of an Electric Circuit Energy Source - to push a charge through the circuit. Wires - transport the electric current Load - changes electrical energy into another form of energy; offer resistance to electric current Examples: light bulbs turn electric current into light and heat 35

To Control the Flow in a Circuit Switch - device used to control the flow in a circuit Open switch - prevents the flow; pathway has a break in it Closed switch - completed pathways so electricity can flow

Types of Circuits Series Circuit All parts are connected in a single loop Only one pathway for electric charges to follow Light glows with same lower brightness as lights are added

Types of Circuits Series Circuit Resistance goes up and current drops (dimmer bulbs) All loads (lights) turn on at the same time A break anywhere in the circuit causes all lights to go out Uses: burglar alarm system

Types of Circuits

Types of Circuits Parallel Circuit  Parts are joined in branches - more than one pathway for the electricity to flow  Potential difference (voltage) across each part is the same  Different branches can have different currents

Types of Circuits Parallel Circuit  All lights glow with the same brightness regardless of how many lights are added  If one light goes out, all remaining lights remain on  can use one device (load) at the time Uses: Electric outlets in a home

Types of Circuits Parallel Circuit

Electrical Power

Electrical Power - the rate at which electrical energy is changed into other forms of energy; measured in watts

How can series and parallel circuits be used to control the amount of electric energy produced?

The resistance in a series circuits is increased by adding loads (slows down the flow of electrons) whereas the resistance in a parallel circuits is decreased by adding loads (increase the flow of electrons).

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