ELECTRICITY Day1

Goals for the Lesson

• Discuss how electricity is created and benefits it bring to

society.

• Understand the principles of electricity and the terms used

when discussing electricity

• Be able to state Ohms Law and its formulas.

• Use a multimeter to measure voltage and resistance.

What is Elecricity

• Definitions

• noun

• any phenomenon associated with

stationary or moving electrons, ions, or

other charged particles

• the science concerned with electricity

• an electric current or charge ⇒ a motor

powered by electricity

• emotional tension or excitement, esp

between or among people

• http://www.collinsdictionary.com

Current Flow

Electricity is the flow of electrons and this flow of electrons is called electric current.

The current flows from negative to positive but due to a lack of understanding about electricity when it first was discovered it was thought it flowed from positive to negative this idea was kept and we call it the conventional current flow

Conductors & Insulators

• Conductors allow current

to flow through them

easily example copper,

aluminium, gold metals

are good conductors

• Insulators prevent current

flowing through them

plastics, wood and rubber

are example of good

insulators

Power source

A power source is required to push the electron around a circuit. The force that pushes the electrons are called volts symbol (V ). The power source can be mains supplied which is Alternating current AC or battery powered Direct Current DC. Alternating current changes from positive to negative in waves called cycles, the ESB supplies alternating current at 220 volts and 50 cycles a second. Direct current flow in the same direction all the times, this is the type of current is stored in a battery

Ohms Law

When we talk about electricity it has a relationship between three values voltage, current and resistance.

Voltage is the force electrons are pushed around a circuit symbol (V ) units volts

Current is the rate or speed the electrons move symbol (I) units ampere (A).

Resistance this is the ability of some conductors to resist the flow of electrons, this allows us to control the flow symbol R units ohms Ω

These three values are expressed in ohms law which states that:

The current flowing through a conductor is proportional to the potential difference across it provided the temperature stays the same. This can be expressed as a formula

Ohms Law Example

Question

What is the resistance of a resistor that has a voltage drop

of 9.35V and a current of 0.55mA

Multimeter

A multi meter is a

device which can

measure voltage,

current, resistance and

check for breaks in

circuits.

Activity

In pairs find the resistance for the resistors given?

Home work

Study work sheet you completed in class.

Complete activity on blog in relation to ohms law.

Find and post back on blog most interesting fact you can

find on electricity.