ELECTRICAL THEORY Flashcards
It is the presence and flow of electric charge
Electricity
Electrical Classification of Materials
Electrical Conductors
Electrical Insulators
Electrical Semiconductors
Electrical Conductors
these are materials that allow the essentially free passage of current when connected to a battery or other source of electrical energy.
Electrical Insulators
these are materials that possess low conductivity or offer a relatively high resistance to the flow of electric current. They are also called as dielectrics.
They are also called as dielectrics.
Electrical Insulators
Electric Semiconductors
these are materials that have conductivity about midway between good conductors and good insulators.
Source of Electric Current
- Static electricity from friction
- Thermoelectricity is electricity from heat
- Piezoelectricity is electricity from pressure
- Electrochemistry is electricity from light
- Magnetoelectricity is electricity from magnetism
Fundamentals Unit of Electricity
- Voltage or electromotive force (E or EMF)
- Amperage or Inductive Flow (I)
- Resistance
Voltage or electromotive force (E or EMF)
_It is the driving force behind current flow. The unit of
electrical pressure is the volt (V).
_Voltage level governs the amount of electrical energy that will flow through a wire.
_A boost in voltage increases current flow and a drop in voltages reduces flow
Amperage or Inductive Flow (I)
it is the rate of current flow in a closed electrical system is measured in a unit called the ampere, frequently called the amp.
___ governs the amount of electrical energy that will flow through a wire
Voltage level
Resistance
-It is the property of a material that limits the amount of flow of current and converts electric energy to heat energy. Its unit is the Ohm.
-The length of a conductor (wire), the diameter of the conductor, type of conductor material, and temperature of the conductor affect the resistance to flow of current.
Ohm’s Law
“At steady-state condition, the voltage across a resistor is directly proportional to the current flowing through it with the temperature remaining constant.”
Ohm’s law
V –
I –
R –
V – applied voltage in volts
I – current drawn in amperes
R – resistance in ohms
Conditions for Ohm’s Law
- Ohm’s law can be applied either to the entire circuit or a part of a circuit.
- When Ohm’s law is applied to a part circuit, part resistance and the potential differences across that part resistance should be used.
- Ohm’s law can be applied to both dc and ac circuit.
Limitations of Ohm’s Law
Ohm’s law is not applicable to the following:
1. For metal which get heated up due to the flow of current through them.
2. For electrolytes where enormous gases are produced on either electrode.
3. For vacuum radio valves.
4. For arc lamps.
5. For semiconductors
6. For gas-filled tubes, in which the ions are generated as a result of current flow.
7. For appliances such as metal rectifier and crystal detectors, in which the operation depends on the direction
of current.
It is the rate at which work is accomplished; it is work or energy released divided by time.
Electrical Power
It is the rate electric charge converted into another form, such as light, heat or mechanical energy (or converted from another form into electrical energy). Its unit is the Watt (W)
Electrical Power
Energy
It is the capacity to do work. It is measured in Joules (J)
Electrical Energy Consumption
It is the rate at which power is consumed over a specified period of time.
Electrical Energy Consumption Formula
E=Pt
Electric Circuit
-It is the collection of electrical elements interconnected in some specific way through which electric current
flows or it is intended to flow.
-A circuit is consisting of a source, conducting parts and a load
Closed Circuit
_It is an uninterrupted path that allows a continuous flow of current through an electrical circuit.
_In a building electrical system, a circuit is closed when a switch is turned on, allowing current to flow uninterrupted and the lamp to light.
Open Circuit
If the path of current flow is interrupted such as if the switch in a circuit is opened (turned off), an open circuit
results.
Short Circuit
_If an inadvertent shortcut develops in a circuit that permits current flow through an unintentional path, a short
circuit is created.
_A short circuit occurs when current leaks out of the intended conductor path such as out of a wire
with damaged insulation.
occurs when current leaks out of the intended conductor path such as out of a wire with damaged insulation.
A short circuit
2 BASIC TYPE OF Circuiting Configurations
Series Circuit
Parallel Circuit
Series Circuit
the circuit elements are said to be connected in series when they all carry the same current.
Properties of Series Circuit
a. The same current flows through all the resistance
b. There will be voltage drop across each resistance
c. The sum of the voltage drop is equal to the applied voltage
Parallel Circuit
circuit elements are connected in parallel when the same voltage is common to all of them.
Properties of a Parallel Circuit
a. The voltage across each resistance of the parallel combinations is the same.
b. There are as many current paths as the number of branches
c. The current in each branch is given by Ohm’s law
d. The total current of the circuit is equal to the sum of branch currents.
P=W/t
Electrical power Formula
