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Chapter 11 Electrical Engineering 245
The engineer might then test the diode to see
that it conducts in forward bias but not in reverse.
Then he or she might test the switch to see that
there is continuity when the switch is closed. The
LED can be tested by applying voltage directly
to the LED to see if it lights. Keep in mind that
a resistor must be used in series with the power
source to protect the LED from excessive current.
Reverse Engineering
Reverse engineering can help electrical engi-
neers solve many problems, but there are ethi-
cal factors to consider. In electrical engineering,
reverse engineering involves taking apart and
studying a component, integrated circuit (IC), or
system to examine how it works so that commer-
cially unavailable parts can be made, problems can
be fi xed, or products can be improved. For exam-
ple, an IC manufacturer might need to recreate a
chip that is no longer available or fi x a problem
with an existing chip design. They might delami-
nate the layers in an IC so they can study and
understand how it works. They can use what they
learn to design a better chip or to recreate it exactly
like the original. Engineers need to be very careful
during reverse engineering to ensure they do not
violate patents or steal someone else’s work.
Electrical Engineering in
Action
Electrical engineers might use their knowl-
edge of electrical characteristics, applications,
and components to take on a project like increas-
ing automobile effi ciency. Gasoline vehicles have
poor gas mileage, are expensive to operate, and
create tremendous amounts of air pollution. Elec-
tric vehicles are much more environmentally
friendly but have been slow in development,
have limited range, and take too long to charge.
So what is the answer?
For answers to most of our modern tech-
nological problems, we look to engineers. One
concept that has rapidly gained popularity is the
hybrid car. Hybrid cars use an internal combus-
tion engine like a conventional car but also use an
electric motor. See Figure 11-31. Hybrid cars are
quick to fuel, have a range similar to that of gaso-
line vehicles, and have less of an environmental
impact than conventional gasoline vehicles.
One of the great gains of the hybrid car is that
it has regenerative braking. When you apply the
brakes in a conventional car, the kinetic energy
from the car’s movement is dissipated in the form
of heat caused by the friction of the brakes. With
regenerative braking, this kinetic energy is used
to turn the electric motor in reverse, which gener-
ates electricity to charge the batteries. This is one
of the reasons hybrids get much better mileage
than conventional cars.
Hybrids are able to operate with a much
smaller gas engine than conventional cars because
the gas engine and electric motor can operate at
the same time when necessary.
When sitting still in rush hour traffi c or at a
red light, conventional vehicles idle, wasting gas.
But hybrids use no energy at all until the driver
presses the accelerator. If battery charge falls
below a certain level, the gas engine will auto-
matically charge the batteries.
Fully electric cars do not pollute the air at
all (except what is created when the electricity is
generated). The biggest drawback with electric
cars is their range because the batteries hold a
limited charge. The batteries must be plugged in
for hours to get a full charge.
Fuel cell cars produce electricity using hydro-
gen and oxygen. This electricity is then used to
power the car. When a battery runs dead, it must
be replaced or recharged depending on the type
of battery. A fuel cell works much the same way,
but a steady fl ow of hydrogen keeps it “charged.”
Fuel cells create zero pollution and the only
by-products are water and small amounts of heat.
Most people agree that we need to stop
burning fossil fuels in transportation or at least
increase the effi ciency of the vehicles we are
using. Hybrid vehicles, plug-in electric vehicles,
fuel cell vehicles, or another new technology
could be the solution to this problem. No matter
what the solution, it will require the best and
brightest scientists, designers, and electrical engi-
neers to change our world for the better.