Page 41 - Electromechanical Devices and Components Illustrated Sourcebook

Chapter 1 Basic Electricity 3

Volt Meter
(volts)
Current Meter
(amps.)

+ −

Electron Flow

Heat

Resistor
Battery Knife Switch (ohms)
Figure 1-4 Voltage, Current, and Resistance

Figure 1-4 shows how these different parameters apply to
Bucket of Water = Battery
our basic electric circuit. Volts are measured at the battery ter-
minals as shown. The voltage will not principally change
Water = Charge
unless the battery is depleted or a load is placed on it that is
greater than it is capable of supplying. Current is measured in
amps by placing a meter in the electrical loop. All current
used flows through the meter and, therefore, it provides a
visual indicator of the current required for the circuit. Output of Bucket = Negative Terminal (−)
Resistance is the load. In the illustration the light bulb is
replaced with a variable resistor. The work generated is in the Pressure = Volts
form of heat.
To get a clearer understanding of the circuit, we can
compare it to the basic water system shown in Figure 1-5.
Flow Rate = Current
An elevated bucket filled with water represents a battery. It
has a stored mass, which can be released when necessary.
The water that flows out of the bottom of the bucket has Paddle Wheel = Resistance
some pressure at this point. This pressure can be equated to
voltage. The higher the pressure, the higher the voltage. The
Valve = Switch
flow rate through the pipes can be compared to current.
Greater flow equates to higher amperage. The paddle wheel
represents resistance. The more load placed on the paddle
wheel, the more resistance to flow it will have. The valve can
be viewed as an on/off switch. When it is closed there is no
Drain = Positive Terminal (+)
flow.
By increasing the amount of water in the bucket, you get
greater capacity from your battery (charge). When you
increase the bucket’s elevation, you increase the pressure
(voltage). By using larger pipes you will get higher flow rates Figure 1-5 Water System Comparison