electrical current. detecting electrical charge electroscope: an instrument to detect electrical...
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Electrical Current Electrical current: the movement of electric charges in a single direction Measured in amperes One ampere = 6250 million electrons moving past a single point every secondTRANSCRIPT
Electrical Current
Detecting electrical charge• Electroscope: an instrument to detect electrical
charge
Electrical Current• Electrical current: the movement of electric
charges in a single direction• Measured in amperes• One ampere = 6250 million electrons moving past a
single point every second
Voltage difference• Voltage difference: electrical charge flows from a
higher voltage to a lower voltage which keeps the electrical flow going• Measured in volts
Electrical Circuit • Electrical circuit: a closed path that electric current
flows through• Batteries: keep the voltage difference maintained
in the circuit in order to keep the current flowing
Dry-Cell Batteries• Dry-cell batteries: 2 electrodes surrounded by an
electrolyte• Electrode: an electric semi-conductor with a carbon
rod that is positive and a zinc part that is negative • Electrolyte: a moist paste containing several
chemicals • Use more batteries to create a higher voltage• Examples: cell phone battery, Duracell batteries,
iPod batteries
Dry-cell Batteries
Wet-cell batteries• Wet-cell batteries: contains 2 connected metal
plates in a conducting solution. The solution transfers electrons which transfers electric charge• Examples: car, truck, boat batteries
Lead-acid Batteries• Lead-acid batteries: wet-cell batteries made up of
lead plates and sulfuric acid solution• Examples: car batteries
Resistance • Resistance: the tendency for a material to oppose
the flow of electrons which changes electrical energy into thermal energy or light energy • Insulators = more resistance • Conductors = less resistance• Measured in ohms (Ω)• Copper: used in household wiring because it
produces less heat
Resistance • Factors that increase resistance of a wire:• Temperature: as the temperature of the wire
increases, the resistance increases• Length: as the length of the wire increases, the
resistance increases• Diameter: as the diameter of the wire increases,
the resistance increases
Ohm’s Law• Ohm’s Law: the current in a circuit equals the
voltage difference divided by the resistance• I = current• R = resistance• V = volts• I = V/R• R = V/I• V = IR
Electrical energy and circuits• Circuits include:1. A source of voltage difference (battery or outlet)2. A device that uses electrical energy (light bulb)3. Conductors that connect the device to the voltage
difference (wires)
Circuits in Series• Circuits in a Series: the current only has one circuit
loop to flow through
Open Circuits• Open circuit: the parts in the series are wired one
after the other, if one part is disconnected, no current flows through the circuit• Example: Christmas lights
Parallel Circuit• Parallel circuit: contains 2 or more branches for
current to flow though• The current can flow through both or one of the
branches at a time• Example: household circuits
Fuses and circuit breakers • Fuses: If the current becomes too
high, a small piece of metal melts and causes a break in the circuit, stopping the flow of current• Circuit breaker: a device that
prevents a circuit from overheating and causing a fire
Electrical Power• Electrical Power: the rate at which electrical energy
is converted to another form of energy• Equation: P = I x V• I = P/V• V = P/I• Measured in Kilowatts because watts are small
units of power
Electrical Energy • Electrical Energy: the power company charges for
the electrical energy used in your home and is measured in kilowatt hours (kWh)• Electrical energy equation: E = P x t• P = E/t• t = E/P