Academic Science - Electricity Notes

SNC1D Grade 9 Academic Science – Electricity Notes Static Electricity ● A stationary electric charge, typically produced by friction, that causes sparks or crackling or the attraction of dust or hair. ● Discharge ○ Building up a charge ○ More electrons flow out of you OR ● Less electrons flow out of you Method of Charging Initial Contact Charge on Between Objects Objects Final Charge Movement Electrons Friction Lots of contact (the Both more objects are contact the neutral greater the charge) Opposite charges (one becomes +ve and one becomes – ve) Move from object with the weak hold on electrons to objects with the stronger hold Conduction/Contact Both One object Attempt to balance Brief touch objects is neutral charge on (no have the One object originally charged rubbing) same is charged object charge Induction (Temporary) Repel/attract in neutral object, depending on the Moving the Both other object’s One object objects objects charge. One side is neutral close have the of the neutral One object together initial object becomes is charged (no charges negatively contact!) they had. charged, but the overall object is still neutral. of Induction (Permanent) Moving the One object objects is neutral close One object together is charged (no contact!) Opposite charges (one becomes +ve and one becomes ve) ● Currents ○ a flow of electricity which results from the ordered directional movement of electrically charged particles. ● Protons, Electrons, Neutrons ○ Electrons: Negative ○ Protons: Positive ○ Neutrons: Neutral ○ Neutrals attract Negative/Positives ○ Negative/Positive attract Neutrals ○ “Likes” repels ○ “Opposite” attracts ○ Same=/=Same ○ Different=Different ○ PROTONS DO NOT JUMP/MOVE!!! ○ Metals, saltwater, have loosely bound electrons that jump to other atoms ○ Something with a stronger hold of electrons can steal electrons from something with a weaker hold ○ Objects that have a stronger hold on electrons tend to be negative ○ Objects that have a weaker hold on electrons tend to be positive ● Insulators: Materials that prevent electrons from freely moving from one atom and one molecule to another. The excess charge will stay where it was when the charge was first applied if it is transferred to an insulator at a specific location. The charge is not evenly distributed across the surface of an insulator because the insulator's particles do not allow for the free flow of electrons. ○ Examples: ■ Rubber ■ Glass ■ Wool ● Conductors: materials that allow electrons to freely move from one atom to another and one molecule to another. In a conductor, electron movement enables charge to be transferred across the object's entire surface. Since electrons are negatively charged, they repel one another until the entire object is charged. ○ Examples: ■ Silver ■ Aluminum ■ Water ○ CONDUCTION: ■ When a charged and neutral object touch and the neutral object turns charged which makes the two object repel each other ■ If a charged object touches a neutral object, the neutral object becomes charged ■ Transfer of charges from the charged object to the uncharged object 1. Initial charge; one is neutral, one is charged 2. Both objects get the same charge 3. Repel after gaining same charge (ex: balloon against wall after friction with hair) ● INDUCTION: ○ Involves the movement of electrons in a neutral object when a charged object is brought close to the neutral object ○ NO DIRECT CONTACT ○ results in opposite charges (permanent) ○ rod → keeps the same charge, object → has the opposite charge (permanent) ○ 2 forms: ■ Temporarily Charge ■ no change in the number of electrons on the object, so object remains neutral ■ rod → stays same charge, object → stays neutral No grounding used ■ is not permanent, TEMPORARY!!!! ■ Permanently Charge ■ when temporarily charged object becomes grounded, it becomes permanent ■ results in opposite charges ■ rod → keeps the same charge, object → has the opposite charge Only when using grounding mechanism and after it gets removed ■ Grounding: a way for electrons to escape the object/way for excess electrons to be removed so a discharge won’t occur. Current Electricity Define: A flow of electric charge is known as an electric current. This charge is frequently carried by moving electrons in a wire in electric circuits. Conductors: Materials that allow the flow of electrons through them, can evenly distribute electrons Insulators: Materials that do not allow the flow of electrons through them, keeps electrons in one place Four parts of a circuit: Circuit is complete if it has all of these components ● Source: Resources for electric power ○ Battery ● Load: A device that transforms electrical energy into heat, motion, sound, or light ○ Lightbulb ○ Sound ○ Heat ● Conducting Wires: A conductor that carries electricity over a distance ○ Copper wiring ○ Humans ○ Any conductor ● Switch: A control device that either allows electrons to flow or stop it. It makes or breaks the current. It is not in every circuit ○ Push switches ○ Toggle switches Circuits: ● ● ● ● ● ● ● ● ● ● The electrons leave the negative side To find the load, there needs to be the purpose (light, sound, or heat) A closed circuit is connected together to let the electrons flow An open circuit has a “break” that disrupts the flow Circuit must be in a full loop Mains electricity is more powerful than battery electricity When the switch is in the off position, we consider the circuit broken Series ○ Pathway for electrons to travel Parallel circuit ○ More than one pathway for electrons to travel 5V = 1 Cell Circuit Symbols and names: Voltmeter: Measures voltage (Not part of the circuit) Ammeter: Measures electrical current Motor: Wat u think a motor does. (used to help make pasta of course) Buzzer: Produces buzzing sound (BROOM BRROOOMMM) Electric Circuit Components Battery (or Source): ● Provides the energy for the electrons ● The battery gives the electrons their energy by lifting them into a higher voltage Conductor (wires): ● Joins all the parts of a circuit. ● Provides a pathway for electrons. ● Allow the electrons to pass along without changing their energy Switch: ● Controls the flow of electrons ● Open = off ● Closed = on Insulator: ● Does not let electrons flow through ● Holds onto them Ammeter: ● Counts the number of electrons passing by a point per second. Voltmeter: ● Counts the energy per electron ● The voltmeter measures how much energy the electron lost while falling through light bulb or gained while raised through the battery Light Bulb: ● Uses up energy from electron Series Circuit: ● Voltage is shared in series circuit ● Current never changes anywhere in a series circuit ● Joules measures the energy in the current (v) (volts= joules per coulomb) (energy= joules) ● Current is the amount of electrons in the circuit Parallel Circuit: ● In a parallel circuit the voltage does not change while the amps are shared ● a parallel circuit is basically more than one series circuits ● when there is more bulb in a series than others, the brightness of the bulbs will be lowered ● Voltage isn’t shared ● Amps is shared Ohm’s Law Resistance, Current, Volts ● R = Resistance ○ R = V/I ● I = Current ○ I = V/R ● V = Volts ○ V=RxI Energy, Power, time ● E = Energy (Joules) ○ Pxt ● P = Power (Watts) ○ E/t ● t = time ○ E/P Efficiency ● Efficiency (%) = useful energy output (J or kJ) x 100% total input energy (J or kJ) kWh – Kilowatt hour ● Multiply kw by the hour