1. DIAGNOSE AND
TROUBLESHOOT
COMPUTER SYSTEMS (DT)
Basic Concepts of Electricity

2. Basic Electrical Terms
Electricity - Is defined as the flow of electron or electric
current. It is an invisible form of energy that can be
transformed into other forms of energy like heat light and
mechanical.
Electron - Is the negatively charged component of an atom. It
has the ability to flow.
Proton- Is the positively charged component of an atom. It
has the ability to attract electron.
Matter- Is anything that occupy space and has mass. It can
be a solid, liquid or gas in state.

3. Atom- Basic component of matter. It composes of a nucleus which is
the central part, the protons and electrons.
Current- Same as electricity or flow of electron. The amount of current
flowing in a circuit can be measured in ampere (I).
Voltage- The amount of pulling force that makes the electron flow. Also
known as potential difference or EMF (electromotive force). The
amount of voltage can be measured in volt (V).
Resistance- Defined as the opposition to the flow of current. The
amount of resistance can be measure in ohms (Ω).

4. Conductors and Insulators
• Conductors are materials that easily allow the flow of current, or it
has a low resistance to current flow.
Examples; aluminum, gold, silver, copper, iron
• Insulators are materials that do not easily allow the flow of current,
or it has a high resistance to current flow.
Examples; rubber, plastic, paper

5. Types of Current
• Direct Current
In direct current (DC), the flow of electric charge is only in one
direction, the type of electricity produced by batteries, static, and
lightning.A voltage is created and maybe stored until it is consumed
when the current flows directly, in one direction.
Example :When you use a flashlight, pocket radio, portable CD player or
virtually any other type of portable or battery-powered device, you are
using direct current.

6. Source: www.electrostudy.com Figure 1.Direct Current
Direct currents flow in one direction only and are constant in time. Their
appearance is that of a straight line which does not vary. They are produced from
power sources such as batteries, power supplies and DC generators. Photovoltaic
devices such as solar cells also generate DC power.

7. • AC Alternating Current
In alternating current (AC, also ac) the movement of electric
charge periodically reverses direction. This type of electricity is
produced or generated by AC generators commonly from a hydro
electric plant. It is the commercial power that we use in homes and
offices. Delivered through a power transmission lines.AC current can be
reduced through the use of power transformer to suite for its
application.It can also be converted to DC for a specific purpose. In the
Philippines AC is rated as 220V AC at 60 Hz.

8. Source: www.electrostudy.com
Figure2. Alternating Current

9. PC’s use only direct current, which means that the alternating
current provided by your utility must be converted to direct current
before use. This is the primary function of your power supply.

10. Electric Circuit
• Electric circuit - is the pathways for electricity to flow.

11. Components of Circuit
• Load - commonly represented by a bulb or any electrical component
that consumes electricity.
• Supply - Commonly represented by a cell or a battery
• Switch - an electrical device that opens or closed a circuit.

12. Figure4. A simple circuit

13. Types of Circuit
• Open Circuit - a type of circuit that has an open path for current to
flow. It means that current cannot flow in open circuit.
Load
Switch
Supply
- +
Figure5. An open circuit
The switch is said to be “OPEN” the current can’t flow into
the circuit and the bulb is “OFF”

14. • Closed Circuit - a type of circuit that has a closed path for current to
flow. It means that current can flow in a closed circuit.
Figure6. A closed circuit
Load
Switch
Supply
- +
The switch is said to be “CLOSED” the current
can’t flow into the circuit and the bulb is “ON”

15. Ged ready for a Quiz Next Meeting