The document discusses basic concepts of electricity and electrical circuits. It defines static and current electricity, and explains that circuits require a voltage source, conductor, and load. Circuits can be connected in series or parallel. Ohm's law defines the relationship between voltage, current, and resistance. Power and energy calculations are also covered.

1. TECHNOLOGY
ELECTRICITY AND
ELECTRICAL CIRCUITS
-
BASIC CONCEPTS
Liezel Oosthuizen
200932201

2. What is electricity?
The flow of electrons in
the form of an electric
charge

3. What are the
two types of
electricity?
a. Static
electricity
b. Current
electricity

4. What is static electricity?
When two objects rub against each other electrons
transfer and build up on an object causing it to have a
different charge from its surroundings.
Like the shoes rubbing against the carpet. Electrons are
transferred from the carpet to the shoes.

5. As electrons collect on an object, it becomes negatively
charged. As electrons leave an object it attains a positive
charges. Charges interact with each other:
Often when you remove clothes
from the clothes dryer, they seem
to stick together. This is because
some of the clothes have gained
electrons by rubbing against
other clothes. The clothes losing
electrons become positive. The
negative clothes are attracted to
the positive clothes.
Have you ever rubbed a balloon on your hair and
stuck it on a wall? How do you think this works?

6. What causes you to be shocked when you rub your
feet across carpet?
An electrical discharge is the passing of an electric
current through the air from a negatively charged object
to a positively charge object. This is what causes
lightning!

7. What is current
electricity?
a. Negative charges
that move along a
path or wire
How is current electricity different
from static electricity?
a. Current electricity travels in a path made
by a wire
b. Static Electricity doesn’t travel in a path
or wire

8. + -
battery junction
wiring terminal
voltmeter V AC generator
ammeter
A Variable
resistance
resistance
Variable
capacitor
capacitor

9. ELECTRIC CIRCUITS
 In an electric circuit, an energy source and an
energy consuming device are connected by
conducting wires through which electric charges
move.

10. All electrical circuits require three elements.
(1) A source voltage, that is, an electron pump usually
a battery or power supply.
[ ENERGY IN]
(2) A conductor to carry electrons from and to the voltage
source (pump). The conductor is often a wire.
[ENERGY TRANSFER]
(3) A load or resistance. A point where energy is extracted
form the circuit in the form of heat, light, motion, etc.
[ENERGY OUT]

11. High Resistance Low
Energy
Energy (Potential Drop) current
current
High Voltage Source Low
Energy
Energy (Potential Rise) current
current

12. What are electric circuits?
Circuits typically contain a voltage source, a wire conductor, and
one or more devices which use the electrical energy.
What is a series circuit?
A series circuit is one which provides a single pathway
for the current to flow. If the circuit breaks, all devices
using the circuit will fail.

13. What is a parallel circuit?
A parallel circuit has multiple pathways for the current to
flow. If the circuit is broken the current may pass through
other pathways and other devices will continue to work.

14. RESISTANCE
Resistance (R) – is defined as the restriction of electron
flow. It is due to interactions that occur at the atomic
scale.
For example, as electrons move through a conductor they are attracted
to the protons on the nucleus of the conductor itself. This attraction
doesn’t stop the electrons, just slow them down a bit and cause the
system to waste energy.
The unit for resistance
is the OHM, W

15. Potential Current Resistance
In volts In amperes In ohms
(joules / coul) (coul / second) (volts / amp)
Drop across a Current passing
resistance Through the
resistor

16. Electrical Calculations – What is Ohm’s
Law?
3V
I=
2Ω
I = 1.5 amps

17. How is Electrical Power calculated?
Electrical Power is the product of the current (I) and the
voltage (v)
The unit for electrical power is the same as that for
mechanical power in the previous module – the watt (W)
Example Problem: How much power is used in a
circuit which is 110 volts and has a current of 1.36
amps?
P=IV
Power = (1.36 amps) (110 V) = 150 W

18. How is electrical energy determined?
Electrical energy is a measure of the amount of power
used and the time of use.
Electrical energy is the product of the power and the
time.
Example problem:
E = P X time
P=IV
P = (2A) (120 V) = 240 W
E = (240 W) (4 h) = 960Wh = 0.96 kWh

19. REFERENCING
 Ch 20 Electric Circuits. (n.d.). Retrieved March 19, 2012, from
http://www.slideshare.net/cscottthomas/ch-20-electric-circuits-online
 Electric circuits. (n.d.). Retrieved March 19, 2012, from
http://www.slideshare.net/jmemler/electric-circuits-10520910
 Electrical Circuits. (n.d.). Retrieved March 19, 2012, from
http://www.slideshare.net/wsautter/electrical-circuits
 Electricity and Magnetism - Basic Concepts. (n.d.). Retrieved March 19, 2012, from
http://www.slideshare.net/makadelhi/electricity-and-magnetism-basic-concepts
 Electricity.Electronics Ch20. (n.d.). Retrieved March 19, 2012, from
http://www.slideshare.net/Wansyi/electricityelectronics-ch20-presentation
 Ohm’s law. (n.d.). Retrieved March 19, 2012, from http://www.slideshare.net/wathens/ohms-law-
7892325
 chapter-12-lesson4-electricity-1216167849986490-8.ppt. (n.d.). Retrieved from
http://s3.amazonaws.com/ppt-download/chapter-12-lesson4-electricity-1216167849986490-
8.ppt?response-content-
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