Understanding Static Electricity

Static Electricity

• Static electricity refers to a stationary electrical charge that accumulates on a material's surface.
• The two types of electrical charges include negative and positive charges.
• Friction can cause electric charges to build up on objects; for example, rubbing a plastic ruler allows it to attract paper scraps.
• Charging by friction refers to the method of charging objects by rubbing them.
• Electrostatics refers to the interaction between static electric charges.
• Static discharge involves a sudden flow of electric current between two objects because of a buildup of static electricity, which causes a spark or shock.
• Matter is composed of atoms, which have positively charged protons, neutral neutrons, and negatively charged electrons.
• Atoms are neutral when the number of electrons equals the number of protons.
• Atoms become negatively charged by gaining electrons.
• Atoms become positively charged by losing electrons.
• Rubbing materials transfers electrons from one material to another but does not create electric charges.
• For example, when a balloon is rubbed against wool, electrons move from the wool to the balloon, resulting in the balloon having more electrons.
• Electronegativity is a chemical property describing an atom's or a functional group's tendency to attract electrons.
• Insulators are materials that do not allow electrons to flow easily and can be easily charged by friction, since gained electrons cannot easily escape.
• Conductors are materials allowing electrons to flow easily and cannot be easily charged by friction, since gained electrons can easily escape.
• Neutral atoms have no overall charge, with the number of protons equaling the number of electrons.
• Only electrons can be transferred to and from an atom, and an atom that is charged is called an ion.
• When a balloon attracts other atom’s electrons when rubbed with a woollen jumper some of the electrons from the jumper will transfer to the balloon, consequently this will leave the balloon negatively charged and the jumper positively charged.
• Opposite charges attract one another.
• Like charges repel one another.

Current Electricity

• Current electricity is caused by moving charged particles, also known as charge carriers
• Moving charges through wires and conductors make up current electricity.
• A current involves a moving charge and charge is a fundamental property of matter that causes it to experience electrical forces.
• Electrons are negatively charged particles that act as charge carriers.
• Charge carriers can also be positively charged particles, called positive ions, or negatively charged particles (negative ions).

Electrical Circuits

• Electricity can be static or current.
• Voltage drop is calculated as Voltage = resistance x current, or V=RI.
• Energy loss, or power dissipated per second, is given by P=I^2R

Electroscopes

• Electroscopes measure electricity and indicate ionization of air by radioactivity.
• Ionization is the process where atoms/molecules gain/lose electrons to become charged ions.
• Radioactivity is energy moving as waves/particles from one place to another.

Voltage, Amperage and Resistance

• Voltage measures the amount of energy supplied to charges by a source or used as they pass through a component (a voltage drop), and it is measured in volts (V) using a voltmeter.
• High voltages indicate that electrons are supplied with or lose much energy while zero voltage indicates a dead battery or an off power point.
• Amperage is the rate of electrical current flow, measured as the amount of electricity flowing through a wire; its unit is the ampere (A).
• Understanding amperage is helpful in designing and maintaining electrical systems because it helps in understanding how much electrical current moves through a circuit.
• Resistance is how much atoms restrict electrons as they pass in wires.
• Resistance measures how hard it is for an electric current to flow.
• High resistance means it is hard for electrons to pass and low resistance means it is easier for electrons to pass
• Energy and voltage lost depend on the material’s resistance, such as bumping into low-resistance materials so almost no energy and voltage is lost and high-resistance having more obstacles.

Reading Voltage and Current with Multimeters

• Voltage is measured in parallel by placing multimeter probes on both sides of a component without breaking the circuit, showing the difference in electrical energy; all parts share the same voltage.
• To measure voltage, set the multimeter, then place the red lead on the positive side and the black lead on the negative side.
• Current is measured in series, so the multimeter must be part of the circuit by breaking it, then connecting the red lead to one side of the break and the black lead to the other, which allows current to flow through to show a reading.

Multimeters

• Multimeters measure electrical potential difference (Voltage), electrical flow (Current) and the opposition to current (Resistance).
• Measured in AC, Alternating Current (household power) or DC, Direct Current (batteries).
• Multimeters also check for complete circuits (Continuity).
• When setting up a multimeter, turn the dial to voltage, current, or resistance.
• Always connect the black lead to the COM port.
• Use the red lead connected to the VΩmA for voltage, resistance, and small currents.
• Use the red lead connected to the 10A/20A for high currents with caution.
• To measure voltage, connect the red lead to (+), and the black lead to (-), then read display.
• To measure current, turn off circuit break at the measurement point, then connect the red lead to (+) side and black to (-) side prior to turning the circuit on and reading the display.
• To measure resistance, disconnect the component, connect the leads to both ends and read display.

Series and Parallel Circuits

• Series circuits connect all components one after another in a single loop and are the easiest to connect.
• Parallel circuits have multiple branching circuits, in which the current leaving the battery splits, with each electron only passing through one globe, unlike a series circuit.

Building and Analyzing Series and Parallel Circuits

• In series circuits, the voltages sum up and the current stays constant.
• The total voltage equals the sum of individual voltages, but the current flows through all parts.
• This helps in troubleshooting and designing circuits effectively.
• Parallel circuits are current dividers with constant voltage: the current splits, with each branch getting a portion based on resistance.
• Homes use parallel circuits so devices get the same voltage but can draw different amounts of current.
• Adding more bulbs in series causes diminishing brightness due to voltage division.
• There is only one current path in series circuits, so the same current flows through each bulb.
• The entire series circuit goes dark when one bulb blows because the current path is broken.
• Bulbs in parallel glow with equal brightness, assuming they are identical, because each bulb receives the full voltage.
• If one bulb fails in a parallel circuit, the alternative current paths allow the others to continue to glow.

Electromagnets

• An iron nail turns into a magnet when taking energy from the battery and turns off when energy is not provided.
• This process makes a solenoid.

Generators and Motors

• A generator converts kinetic energy to electrical energy using electromagnetic induction to produce a voltage at power stations.
• In electromagnetic circuits, ammeters are also called galvanometer.

Generators

• Despite the portability of batteries, generators that utilize electromagnetism become necessary to generate electricity in homes and industries.
• Electricity is produced from Movement and magnets.

Circuits

Series

• Series circuits function by connecting parts, like light bulbs, one after another in a single loop.
• Electricity only has one path, so if one part breaks, the whole circuit goes out and voltage source divides up between each part.

Parallel

• Parallel circuits function by connecting parts side by side, so electricity can take multiple paths.
• If one part of a parallel circuit breaks, the other parts keep working since they have alternative paths the electricity can travel through.

DC motors

• DC motors utilize magnetism to transform electricity into movement with the assistance of the rotor (which spins) and the stator (which holds two magnets).
• When electricity flows through the rotor's wires, a magnetic field is created, which interacts with the stator's magnets to spin the rotor.

Relationship of voltage and current

• If voltage increases then the current also increases, and if voltage decreases then the current also decreases.

Parts of a Circuit

• Battery: Supply electrons
• Cell: Add voltage
• Armature: Produce electrons
• Ammeter: Measures current.

Definitions

• Ammeter: Measures current.
• Battery: Has 2 cells.
• Conductor: Allows current to pass.
• Current: Flow of charge.
• Armature: Part carrying alternating current (AC).
• Electromagnet: Solenoid with iron rod.
• Electrolyte: Solution/paste conducting electricity.
• Generator: Uses electromagnetism to produce electricity.
• Insulator: Blocks current.
• Static electricity: Buildup of electric charge.
• Voltage: Energy provided/used; measured in volts (V).
• Voltmeter: Measures voltage.
• Magnetism: Force between attracting/repelling magnets.
• Electrostatics: Study of electromagnetic phenomena.
• Ampere: Unit of electrical current.
• Ohm (Ω): Unit of electrical resistance.
• Amperage: Amount of electrical charge flowing.
• Resistance: Difficulty for current to pass; measured in ohms (Ω).
• Solenoid: Rod with iron coiling around it.
• Alternating current (AC): Current shuffles back and forth.
• Direct current: Current travels in one direction.
• Fuse: Safety device that interrupts the circuit if the current becomes too strong.
• Cell: Converts chemical energy into electrical energy.
• Multimeter: Measures amps and volts.