# Computer Operating Systems

#### Urban Voice -- Instructor: Lenny Bailes

Day 17 Agenda

Please be on time and attempt to bring all of your materials with you to
class each day. Even if we haven't worked with an Exercise Sheet or the
Meyers lab manual for awhile, they may still be relevant to what we're doing in class.

Always bring

The A+ in Depth textbook
Your recent class notes, daily agenda sheets, and flashcards
A notebook to take notes on the current day's activities.
At least two 1.4MB floppy disks -- one to store files and one to use in formatting
exercises

I will usually post the agenda sheet for the day at least a few hours before
class begins. If you have Internet access, you can check the daily agenda before
coming to class.

1.  Finish DOS Exercise sheet and review of DOS commands in Chapter 3 (see Day 16 Agenda)

2.    Discussion of Chapter 4 Concepts (Electricity)

Use Chapter 4 of Andrews, A+ in Depth to fill in the answers to these questions.
One key to understanding electricity is to visualize it as a flow of electrons, similar to the flow of water      molecules that flow along a path of least resistance.

a)  An electric circuit is a ________ system. Water flows because of the force of gravity. Electrons flow
because

______________________________________.

b)  The difference in charge in an electric current is called ___________________________.   Electrons move

from a __________________ charged or _______ location to a ______________________ charged

location, sometimes called the ______________.

c)   Typically, we measure electrical energy in four ways, each with its own unit properties.

 Unit What is it? Symbol

d)  Voltage, or ____________________ is similar to water pressure.   When you force the flow
of water through a thinner hose, what happens to the water pressure within the house?

______________________________________________. What do you think happens to

voltage, if you force a current through a thinner wire? _________________________.

e) Amperage, sometimes called __________________ measures _____________________
flowing through an electrical system.

If you pour a gallon of water through a thin pipe, the total amount of water that flows out the
other end is the same as when you pour the gallon of water through a wide pipe.

If you measure the electric current flowing through any part of a simple circuit, its amperage
value is __________ to the quantity of current flowing through another part.

f)  If a constant stream of water from a pipe turns a water wheel and you turn a valve to allow flow
through a wider surface area, the water will flow faster. Decreasing the _________ to the flow
increases the speed of the water wheel.

_________________, measured in ohms, is the property that blocks the flow of electrons in an
electrical circuit and its conducting medium.that blocks the flow of electrons. If the blockage of
electrons is low enough to allow a complete circuit (electrons can flow from negative to positive
terminals), the circuit is said to have ____________.

Reducing the size of a wire through which a current flows _______________ the amount of electricity
that  can safely flow through it. If too much electricity (an overload) flows through a wire, this creates

__________________________, which can melt the the wire.    Can you think of a common household

safety device that makes use of this principle.? _______________________________.

g)  Voltage and current (amperage) have a direct relationship.  If you increase the voltage through a closed
circuit, the amperage _________________.

Resistance has an inverse relationship with voltage and current. If the resistance (blockage) to an electric

circuit increases, then either _____________ or ______________ will decrease.

h)  Power, measured in _________, is the total electrical energy needed to operate a device, taking into
consideration the amount of current available, and the electrical pressure (voltage) of the circuit.

Wattage is calculated by multiplying ___________ times _____________.

Homework:

Study for
Chapter 3 Quiz on Tuesday!

Review A+ in Depth, Chapter 4,  p. 125-152. Fill in as many blanks as you can in today's agenda sheet and write out answers to questions 1-6 on p. 172-173

Think about a research project/report that you might be interested in doing for the class. We'll discuss
this in more detail, next week.

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