grade 9 - electricity

• Resistance?


  Unit name: Ohms

  Metaphor: things that flow slow
• Current?


  Unit name: Ampere

  Symbol: Amps

  Metaphor: Rate of the flow down
• Voltage?


  Unit name: Volts

  Symbol: V

  Metaphor: potential energy
• Two types of circuits are series & parallel
• Any breaks in a series circuits means?

  The circuit will fail.

  Ex: both light bulbs die
• Parallel Circuit: A circuit in which the current is split between two branches, if a failure occurs one branch will continue to flow.
• Wires are used to move electrons through circuits.
• Metals are used to create wires because electrons are passed quickly from atom to atom. Metals are good conductors for electron movement.
• Non-metals slow the flow of electrons by trapping them, they are resisturs and insulators for electron flow.
• Equation for Ohm's Law: V = I x R

  (V - voltage, I - current, R - ohms)
• A closed switch can cause electricity to move in a circle, when the switch is opened though the electrons stop flowing at the switch.
• Static Electricity defined?

  One way transfer of energy.
• In static electricity opposites attract. Protons and electrons are drawn together from to objects to create balance or a neutral charge.
• Positives to Static Energy?


  Quick release of energy.
• Negatives to Static Energy?


  Fire, electric shock, unpredictable, hard to create and produce a charge inbalance, happens once and not continous.
• Electrons and protons in an atom balance out.
• What is a Charge Imbalance or Net Charge?


  Rubbing or friction can give electrons enough energy to leave their atoms and attach to others. When this happens the first object is left with more protons and becomes positively charged. Another object is left with more electrons.
• How does the Neutral Charge Equilibrium get restored?


  Negatively charged objects comes in contact with positively charged object the electrons jump, neutralizing.
• Static discharge is electrons balancing.
• The current is the flow of negatively charged electrons.
• The higher resistance the more difficult it is for a current to flow.
• Voltage is like the force pushing the current around.
• Resistance in wire is effected by material, thickness and the length of the wire.
• Temperature can also effect resistance in wires, the higher the temperature the more resistance.
• Resisturs: Rheostat - dimmer switch, physically changes resistance. Thermostat - as temperature changes so does the resistance. Varistor - changes resistance based voltage, surge protector, high the volts = higher the resistance.
• In series circuits, if one bulb goes out then they will all go out because there is only one pathway for the current to follow.
• Parallel circuit has higher total resistance than a series circuit.
• Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams.
•  Alternating Current (AC) is a type of electrical current, in which the direction of the flow of electrons switches back and forth at regular intervals or cycles. Current flowing in power lines and normal household electricity that comes from a wall outlet is alternating current.
• The process of coating a metal, usually of iron, nickel, or copper, with another metal. The base metal is placed in water, and is gradually coated with particles of another metal is electroplating.
• An electrochemical cell in which the electrolyte is a paste is a dry cell.
• An electrochemical cell in which the electrolyte is liquid is a wet cell.
• As more resistors are added to a parallel circuit the total resistance decreases.
• Lightning rods are designed to protect a house or building from a direct lightning strike and, in particular, a lightning-initiated fire
• Three devices that use static electricty are?

  Photocopiers

  Laser printers

  Electrostatic air filters