Chapt& 11 Elec-icity and Its Production
11.1 Electrical Energy and Power Plants
What is Electricity?
It refers to electrical energy and the movement of charge and is transferred through conduc8ng wires in
transmission lines.
Electrical Power (P)
➲ The rate of transforma8on of electrical energy.
➲ Equals to the word “power”.
➲ Expressed in waDs (W).
Measuring Electrical Energy
Electrical energy is measured in units of kilowatt hours (kWh) because the joule (J) is something too small to
be a convenient measurement.
KilowaD hour (kWh)
➲ Measure of electrical energy.
➲ One kilowaD hour is equal to 3.6 million joules.
Summary
v Mechanical energy, thermal energy, and radiant energy are transformed into electrical energy in
power plants.
v Electrical power is the rate at which electrical energy is generated or transformed.
v Electrical energy is measured in units of kilowaD hours (kWh) for homes and megawaD hours
(MWh) for power plants.
1
, 11.3 Electric Potential Difference
Electric Poten8al
➲ The amount of electric poten8al energy associated with charges.
➲ Measures both electrical energy and the quan8ty of electrons.
𝑱 𝑱
➲ Unit: Joule per coulomb ( ) ; 1 = 𝟏𝑽
𝑪 𝑪
o Joule is a measurement of the electric poten8al energy.
o Coulomb is a measurement of the number of electrons or amount of charge.
Electric Poten8al Difference (𝑽)
➲ The change in electric poten8al energy associated with charges at two different points in a circuit.
➲ Referred to as voltage (𝑽)
∆𝑬
𝑽=
𝑸
where V = electric poten8al difference (joules per coulomb or volts)
∆E = change in electric poten8al energy (joules)
Q = the amount of charge (electrons) (coulombs)
Symbol:
Voltmeter
➲ Electrical device that measures electric poten8al difference.
Summary
v Free electrons that are able to move are essen8al for the transfer of electrical energy.
v Electric poten8al is a measure of how much electric poten8al energy is associated with charges.
v Electric poten8al energy difference, or voltage, indicates the difference in electric poten8al
energy of the charges (electrons) between two points in a circuit.
∆$
v The equa8on for electric poten8al difference is 𝑉 = %
.
𝑱
v Electric poten8al difference is measured in 𝑪 or 𝑉.
v The amount of charge or number of electrons (𝑄) is measured in coulombs.
v Voltmeters measure electric poten8al difference and are connected in parallel in a circuit.
v Sources of electrical energy cause an increase in the electrical poten8al (voltage gain), whereas
loads cause a decrease in the electric poten8al (voltage drop).
2
11.1 Electrical Energy and Power Plants
What is Electricity?
It refers to electrical energy and the movement of charge and is transferred through conduc8ng wires in
transmission lines.
Electrical Power (P)
➲ The rate of transforma8on of electrical energy.
➲ Equals to the word “power”.
➲ Expressed in waDs (W).
Measuring Electrical Energy
Electrical energy is measured in units of kilowatt hours (kWh) because the joule (J) is something too small to
be a convenient measurement.
KilowaD hour (kWh)
➲ Measure of electrical energy.
➲ One kilowaD hour is equal to 3.6 million joules.
Summary
v Mechanical energy, thermal energy, and radiant energy are transformed into electrical energy in
power plants.
v Electrical power is the rate at which electrical energy is generated or transformed.
v Electrical energy is measured in units of kilowaD hours (kWh) for homes and megawaD hours
(MWh) for power plants.
1
, 11.3 Electric Potential Difference
Electric Poten8al
➲ The amount of electric poten8al energy associated with charges.
➲ Measures both electrical energy and the quan8ty of electrons.
𝑱 𝑱
➲ Unit: Joule per coulomb ( ) ; 1 = 𝟏𝑽
𝑪 𝑪
o Joule is a measurement of the electric poten8al energy.
o Coulomb is a measurement of the number of electrons or amount of charge.
Electric Poten8al Difference (𝑽)
➲ The change in electric poten8al energy associated with charges at two different points in a circuit.
➲ Referred to as voltage (𝑽)
∆𝑬
𝑽=
𝑸
where V = electric poten8al difference (joules per coulomb or volts)
∆E = change in electric poten8al energy (joules)
Q = the amount of charge (electrons) (coulombs)
Symbol:
Voltmeter
➲ Electrical device that measures electric poten8al difference.
Summary
v Free electrons that are able to move are essen8al for the transfer of electrical energy.
v Electric poten8al is a measure of how much electric poten8al energy is associated with charges.
v Electric poten8al energy difference, or voltage, indicates the difference in electric poten8al
energy of the charges (electrons) between two points in a circuit.
∆$
v The equa8on for electric poten8al difference is 𝑉 = %
.
𝑱
v Electric poten8al difference is measured in 𝑪 or 𝑉.
v The amount of charge or number of electrons (𝑄) is measured in coulombs.
v Voltmeters measure electric poten8al difference and are connected in parallel in a circuit.
v Sources of electrical energy cause an increase in the electrical poten8al (voltage gain), whereas
loads cause a decrease in the electric poten8al (voltage drop).
2
