Electricity Study Guide PDF

Electricity: Electricity- the flow of electrons Electric Charge (Coulomb)- an electrical property of manner (positive, negative, neutral) - Charge is never created or destroyed - Like charge repel, opposite charge attract - Charges come from an imbalance in protons and electrons - Negat...

Electricity: Electricity- the flow of electrons Electric Charge (Coulomb)- an electrical property of manner (positive, negative, neutral) - Charge is never created or destroyed - Like charge repel, opposite charge attract - Charges come from an imbalance in protons and electrons - Negative charge (More electron than protons) - Positive charge (More protons than electrons) - Neutral charge (equal protons and electrons) *ELECTRONS MOVE-PROTONS DO NOT Electrical Conductors- allow electrons to move freely (metals and copper) Electrical Insulators- Don’t allow electrons to move freely (plastics, cardboard, glass, silk) Static Electricity- The build up of charge on an object- BUILD UP IN 3 WAY - Induction- The process of inducing a charge on a object (NO TOUCHING)- create unbalanced charges to object nearby - Conduction- the process of transferring charge (OBJECTS TOUCH)- charge moves from one object to another - Frictions- Charges are transferred when two objects move against each other - you can see the charge buildup if it is big enough Electrical Force- The force due to the attraction of repulsion of two charged particles - Everyday forces - Depends on charge and distance between particles Electrical Field- A field that exists in the space around a charged particle - How we show electrical forces - Other particles in field will experience electric force - Field lines (positive point out, negative points in) - Electrical field lines will NEVER cross Current and Circuit: Electrical Potential Energy- energy that depends on its position in an electric field field - Depends on charge and distance Potential difference- (VOLTAGE)-charge in the electrical potential energy of a charged particle in an electric field divided by its charge (VOLT) - Batteries have voltage - Voltage tells the potential difference between two terminal of the battery - Batteries are electrochemical cell that convert chemical energy into electrical energy Dry cells- electrolyte paste (AA batteries) Wet cells- electrolyte is a liquid (car batteries) Electrical Current- the rate at which the charges move through a wire (SI unit- Ampere) - Direct current- the charge always move from one terminal to the other in the same direction - Alternating current- current where the flow of electrons can switch directions at regular intervals (house plugs) - Conventional Current- current made of positive charges…opposite to the direction that electrons move (solutions, gases) Resistance (Ohm)- caused by internal friction- slows the movement of charges through a conducting material- used to control the current - Thickness, length, and temperature can impact resistance of a substance Electrical Conductors- materials that transfer electrons easily - have low resistance Electrical Insulators- materials that don’t transfer electrons easily- have high resistance (rubber) Semiconductors- have properties of both conductors and insulators- mixture of atoms (silicon, boron, germanium) Superconductors- have zero resistance when the temperature falls below a critical temperature- when voltage is gone, current still flows (mercury, tin, commuter trains) Ohm Law- V=I*R Voltage=Current (A)*Resistance(Ohm) Electric circuit- a path where electrons flow that includes wires and source of voltage - Closed Circuit- a circuit where the electrons can flow freely - Open Circuit- a circuit where electrons cannot flow freely- no complete path Switch- used to open and close he path for the circuit - if switch is open, the circuit will be open, if it is closed, the circuit will be closed Schematic Diagram- a diagram that depicts the construction of an electrical circuit or apparatus - Includes wires, voltage source, resistors- anything in circuit Series Circuit- A circuit where voltage is divided among the devices and there is ONE path for electrons to flow - Current in each device is the same- but voltage can be different - If there is a break in the circuit, the entire thing won’t work - More light bulbs means more resistance so they are less bright Parallel Circuits- a circuit where the voltage is the same across multiple paths for electrons - Each resistor has its own path - Voltage is the same in all device but the current of each equals the total current of circuit - If one breaks, it doesn’t make them all stop - Each lightbulb gets same voltage so they shine brighter Electrical Power (SI unit Watt)- the rate at which electrical energy is changed to other forms of energy 2 2 - 𝑃 = 𝐼 * 𝑉 = 𝐼 * 𝑅 = 𝑉 /𝑅 Electricity: Electrical + Magnetism- Electromagnetic Force - Electromagnetic Waves (light) are made from changing electric and magnetic forces - These two forces are perpendicular and the wave travels in a third direction - The magnetic field is perpendicular to the flow of the current - Use the right hand method Solenoid- wrapping the wire around into a coil that carries current and produces a magnetic field - Increases the magnetic field because each coil adds together and makes larger field - Acts similarly to a permanent magnet - More loops or stronger current means stronger magnetic Electromagnet- a rod made of magnetic meta is surrounded by a solenoid with current passing through it - Extremely strong because the magnetic field of solenoid adds to field of rod - Make it stronger by adding coils, or add magnetic metals Electric Motors- machines that convert electrical energy into mechanical energy - Perform work when attached to other device - Magnetic field created by current interacts with a magnet near the wire - The interaction causes rotation and mechanical energy Galvanometers- devices that use solenoids to measure current or voltage - Used with ammeter (measure current) and voltmeters (measures voltage) Electromagnetic Induction- the process of creating a current in a circuit by changing a magnetic field - When you move a magnetic in and out of a coil - FARADAY'S LAW - Loop of wires cannot be parallel to movement of magnetic field (90 degrees is best) - Current can be induced if circuit is rotated in a magnetic field or if strength of field is changed  - It obeys the law of conservation of energy because work is required to push the magnetic field through loop Generator- convert mechanical energy to electrical energy - Alternating current (AC)- changes in regular intervals - Rotating coil or magnet- ONLY one moves - Power plants use hydroelectric generators or coal to produce steam - Transformer- devices that increase or decrease voltage going in = the power going out - Voltage is changed so current changes too - Too much current through wires can cause fires Fuse- A ribbon of wire that has a low melting point - The fuse melts and stops the current flow A circuit breaker- uses a magnet or bimetallic strip that responds to current overload by opening the circuit Grounding- the transfer of excess charge through a conductor to earth Magnetism: - Magnets have poles with opposing properties (North, South) like poles repel each other, opposite poles attract - It is impossible to isolate poles Magnetic Pole- if a magnet is cut, the cut ends change to other poles Permanent Magnets- objects that are magnetized all the time - Magnetism can be weakened or removed by hammering or extreme temperatures Magnetic hard substance- difficult to magnetize but don’t lose it easily (cobalt, nickel) Magnetic Soft Substance- - Magnets exert a force on substances that are “soft”- soft objects become magnets too Magnetic Force- the force a magnet exerts on another magnet or on moving moving charges - Closer an object is to the magnetic field, the stronger the force is Magnetic Field- a region where a magnetic force can be deteced