Transcript 3.3 Electrical Rate Notes

Chapter 3.3
Notes
Rate in Electrical
Systems
• Speed is the rate of change of
position.
• Acceleration is the rate of change
of velocity.
• Volume Flow Rate is the rate of
change of volume.
• Mass Flow Rate is the rate of
change of mass.
• In electrical systems, the most
important rate is Current.
• When a conductor joins two objects
of different voltage, charge flows from
the higher potential to the lower
potential.
• The Voltage is the prime mover that
causes charge to move.
• In a solid conductor, it is the
electrons that move in the circuit.
• Current is a measure of the charge
that passes through the area in a time
interval.
• The electric current (I) =
Charge / time
• Charge is measured in
Coulombs (C).
• Current is measured in
Amperes (A).
• I=q/t
• A current of 7 amperes
occurs in 10 seconds,
what is the charge
moved?
• I=q/t
• 7 = q / 10
• q = 7 x 10 = 70 C
• You can measure current
in electrical systems with
an ammeter and measure
potential difference
(voltage) with a voltmeter.
• Current = Ammeter
• Voltage = Voltmeter
• An ammeter measures Current
through a circuit element.
• An ammeter must be placed in the
conducting path so the current
through the circuit is the same as the
current through the ammeter. This is
called a Series connection.
• A Voltmeter measures the
potential difference or voltage
across a circuit.
• The load (light bulb) and the
voltmeter are placed parallel to
each other so that the voltage
across the voltmeter is the same
as that across the light bulb. This
is called a parallel connection.
Voltmeters and Batteries
• Frequency is a
measure of how often a
pattern repeats itself.
• The equation for
frequency = Number of
Cycles / time
• f=n/t
• If a wave has a frequency of
60 cycles per second during a
5 second interval, how many
cycles or waves will occur?
• f=n/t
• 60 = n / 5
• n = 60 x 5
• n = 300
• The Period of a
repeating pattern is the
time it takes for one
complete cycle.
• The equation for period
= 1/frequency
• T = 1/f or f = 1/T
• If we have a frequency of
4000, what is the period? If
we have a period of .002, what
is the frequency?
• T = 1/f ; f = 1/T
• T = 1/4000 = .0003
• f = 1/T
• f = 1/.002 = 500