Understanding Current Electricity & Circuits

• Current electricity involves the movement of charges in a continuous flow.
• An electrical current flows until it is used up or disconnected.
• The flow of electricity resembles water flowing until it is dammed or its source ends.

Conductors

• Conductors are materials that allow electrical energy to move easily through them.

Circuits

• A circuit is a path that manages the flow of electricity, water systems use with pipes and taps to manage the flow of water.
• Electricity flows along solid metal wires in most pathways, but circuits can also incorporate gases and other fluids.

Parts of a Circuit

• A complete electrical circuit includes a load, an energy source, and a conductor.
• LOAD: A device that converts electrical energy to another form, such as a lightbulb.
• ENERGY SOURCE: The origin of electrical energy, for example, a battery.
• CONDUCTOR: A pathway for electricity to flow, such as wires.

Electric Current

• Electric current is the total amount of charge passing through a wire over a given period.

Voltaic Cells

• A voltaic cell is an electrochemical cell that uses a chemical reaction to produce electrical energy.
• Two different types of metals, known as electrodes, are necessary to create the reaction in a voltaic cell.
• Multiple cells can be connected.

Ampere

• Symbol: A
• The rate at which current flows is measured in amperes, or amps for short.
• An ampere is a unit of measure for the rate of electron flow or current in an electrical conductor.
• One ampere of current means one coulomb of electrical charge moving past a specific point in one second.

Resistance

• Symbol: R
• Resistance measures the force opposing the flow of current in a circuit.
• It indicates how difficult it is for a current to flow.
• Resistance is measured in ohms, represented by the Greek letter omega (Ω).
• Ohms are named after Georg Simon Ohm, a German physicist (1784-1854) who studied the relationship between voltage, current, and resistance.
• Factors affecting resistance:
  • Temperature: higher temperature equals more resistance.
  • Length of wire: longer wire equals more resistance.
  • Diameter of wire: thinner wire equals more resistance.
• Some materials conduct electricity better than others, copper conducts better than iron.

Voltage

• Symbol: V
• Voltage measures the amount of electrical energy carried by each particle and is also known as "potential difference."
• Voltmeters are tools that measure voltage.
• A red lead must run to the positive battery terminal.
• A black lead must run to the negative terminal.

Power

• Symbol: P
• Power is a measure of how much energy is used over time.
• Units of power are called Watts.
• Named to honor James Watt, the inventor of the steam engine.
• One Watt is a small amount of power.
• Formula: Power = current x voltage or P = IV, where P = Power, I = Current, and V = Voltage.

Electric Eels

• Electric eels use electricity to kill or stun prey, defend themselves, and communicate.
• Large electric eels can grow up to 2.4 m long and discharge enough electricity to kill a human.
• The electricity is produced by a special organ in the tail that contains thousands of modified muscle cells called electroplaques.
• An eel releases an electrical charge to stun prey, and these flows are so strong they have even been known to knock down a horse.