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Electrical Quantities and Ohm’s Law
A coulomb is a quantity measurement for electrons. One coulomb contains 6.25 x 1018 electrons, or 6,250,000,000,000,000,000 electrons.
Electrical Quantities and Ohm’s Law
The ampere is a measurement of the amount of electricity that is flowing through a circuit.One ampere (A) is defined as one coulomb of electricity flowing past a given point in one second.
Electrical Quantities and Ohm’s Law
There are two theories about current flow. Electron flow theory describes current flow from negative to positive. Conventional current flow theory states electrical current flows from positive to negative.
Electrical Quantities and Ohm’s Law
Electrical sources are divided into two basic types:• Direct Current (DC) which is unidirectional (one
way). • Alternating Current (AC) which is bidirectional
(two way, or back and forth).
Electrical Quantities and Ohm’s Law
A complete path must exist before electricity can flow through a circuit. A circuit with a complete path for electrical flow is called a closed circuit. If the circuit path is incomplete or broken, this is called an open circuit.
Electrical Quantities and Ohm’s Law
The basic principle of the instantaneous effect of electric impulses.
Electrical Quantities and Ohm’s Law
The impulse of electricity can travel faster than light. It would take light 1.3 seconds to travel around the earth 10 times. If a wire were wrapped around the earth 10 times, when the switch was closed the light would come on almost instantly.
Electrical Quantities and Ohm’s Law
An ohm is the unit of resistance or opposition to the flow of electricity.
Electrical Quantities and Ohm’s Law
Ohm’s law states that in a DC (Direct Current) circuit, the current is directly proportional to the voltage and inversely proportional to the resistance.
E (volts) = I (amps) x R (ohms)
Electrical Quantities and Ohm’s Law
Ohm’s Law Symbols:P is the symbol for Watts.E is the symbol for Volts.I is the symbol for Amperes.R is the symbol for Resistance or Ohms.
Electrical Quantities and Ohm’s Law
Ohm’s Law states that it takes one volt to push one ampere through one ohm.
E = Volts
I = Amps
E = I x RI = E / RR = E / I
R = Resistance
Electrical Quantities and Ohm’s LawAdding P (watts) to the Ohm’s law chart.
P = E2 / RP = E x IP = I2 x R
R = E / IR = P / I2
R = E2 / P
I =I = P / EI = E / R
E = E = I x RE = P / I
Electrical Quantities and Ohm’s Law
Remember:E = EMF, or voltageI = intensity of current, or amperageR = resistance in ohmsP = power in watts
E (volts) = I (amperes) x R (ohms)P (watts) = I (amperes) x E (volts)
Electrical Quantities and Ohm’s Law
Review:
1.A coulomb is a quantity measurement of electrons.
• An ampere (A) is one coulomb per second.• Either the letter I, which stands for intensity
of current flow, or the letter A, which stands for amperes, can be used in Ohm’s law formulas.
Electrical Quantities and Ohm’s Law
Review:
1.Voltage is referred to as electric pressure, potential difference, or electromotive force. An E or a V can be used to represent voltage in Ohm’s law formulas.
• An ohm (Ω) is a measurement of resistance (R) in an electric circuit.
Electrical Quantities and Ohm’s Law
Review:
1.The watt (W) is a measurement of power in an electrical circuit. It is represented by either a W or a P (power) in Ohm’s law formulas.
• Electric measurements are generally expressed in engineering notation.