Download Module 8 Lesson 1 Notes Presentation Guided Notes KEY What is

Module 8 Lesson 1 Notes Presentation Guided Notes KEY
What is electric charge?
There are positive and negative charges. An atom has equal numbers of protons and electrons,
which means that the positive and negative charges cancel out. So, an atom has no net electric
charge. It is said to be electrically neutral.
When there are transfers of charges, it is STATIC ELECTRICITY. For example, when the
electrons are transferred from the carpet to your shoes, the accumulation of excess electric
charge on your shoes is called static electricity.
Electric charges exert forces. Unlike charges attract each other. Like charges repel each other.
As the distance between charged objects increases, the attractive force decreases. Conductors
are materials in which electrons can easily flow. For electricity, the best conductors are metals.
The atoms in metals have loosely held electrons that make it easy for electricity to flow through
them.
Insulators are materials in which electrons cannot easily flow. Unlike in conductors, electrons in
insulators are held tightly, such as in plastics. Plastics cover electric cords to prevent you from
getting shocked.
Because electrical forces act at a distance, charged objects brought near a neutral object will
cause electrons to rearrange their positions on the neutral object. This charging at a distance is
induction.
When two charged objects are touched to each other, electrons will rearrange their positions
between each other. This charging by touching is conduction.
When two different types of materials are rubbed together, the charged particles will rearrange
themselves on each object. This charging by touching of two different materials is charging by
friction.
Let’s look at lightning. Eventually, enough charge builds up to cause a static discharge between
the cloud and the ground. As the electric charges move through the air, they collide with atoms
and molecules. These collisions cause the atoms and molecules in air to emit light. Lightning
also creates powerful sound waves. The electrical energy in a lightning bolt rips electrons off
atoms in the atmosphere and produces great amounts of heat. The heat causes air in the bolt's
path to expand rapidly, producing sound waves that you hear as thunder.
A discharge can occur any time that charge builds up in one area. Providing a path for charge to
reach Earth prevents any charge from building up. Earth is a large, neutral object that is also a
conductor of charge. Any object connected to Earth by a good conductor will transfer any
excess electric charge to Earth. Connecting an object to Earth with a conductor is called
grounding.
Forms of Electricity
Electricity occurs in two different forms:
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Static
This type of electricity is stationary. It occurs in one place at one time.
Current
This type of electricity moves. It flows around a circuit.
Static Electricity occurs with materials which are insulators, such as plastic. Rubbing adds or
removes electrons, so the rubbed object becomes charged. Remember: Like objects repel,
unlike attract.
Current Electricity is when electrons flow through a conductor, such as copper. Flow is from
negative to positive and circuits create a continuous loop for electrons to flow. Requires an
energy supply, but also, it uses energy.
CIRCUIT TYPES
The simplest type of circuit involves electricity going around with no “choices” (electrons don’t
really choose). This is called a Series circuit.
The other main type of circuit has two or more branches. This is called a Parallel circuit.
Series circuit has a single loop for electrons to travel around, so they can only go in one
direction. Components are connected one after another, or in “series”. Current has to travel
through all components and current is the same at all points. Voltage is shared between
components.
Parallel circuit has two or more paths for electrons to travel, so electrons have options. Current
is shared between the branches and the sum of the current in each branch equals total current.
Voltage loss is the same across all components
Electricity is forced around a circuit by an electrical force field. Flow of electricity around a
circuit is called CURRENT (I) and it is measured in amps (A). Voltage (V) is the increase or
decrease in the amount of electrical energy carried by the current.
Current (I) is the flow of electrons around a circuit. DC is direct current, such as in a battery that
you would put in a flashlight. In DC currents, electrons flow in one direction. AC is Alternating
current, such as the current that runs through your home. Electron flow changes direction 50x
per second.
Ammeter measures CURRENT(I), which is the flow of electrons. The unit is Amps (A). To
measure Amps, connect the ammeter in the series at the point you wish to measure.
Voltage (V) is the gain or loss of energy as it passes through a component. Voltage lost equals
voltage gained. In series circuits, voltage loss is shared between components. In parallel
circuits, voltage loss is the same across all components. Voltmeter measures voltage in Volts
(V). Voltage increases as it passes through energy suppliers. Voltage is decreased as it
passes through energy users. To measure voltage, connect voltmeter in parallel circuit around a
component.
Power is energy used by component per second and is measured in the unit of the Watt, symbol
is W. One watt means that 1 joule of electrical energy is being used up per secondHousehold
Circuits
The wiring in a house must allow for the individual use of various appliances and fixtures. This
wiring is mostly a combination of parallel circuits connected in an organized and logical network.
The main switch and circuit breaker or fuse box serve as an electrical headquarters for your
home. Parallel circuits branch out from the breaker or fuse box to wall sockets, major
appliances, and lights.