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Power point by Salma Hamamy

ELECTRICITY

• Electricity is a form of energy resulting from the existence of charged particles (such as electrons or protons), either statically as an accumulation of charge or dynamically as a current.

• Electricity lights up our homes, cooks our food, powers our computers, television sets, and other electronic devices. Electricity from batteries keeps our cars running and makes our flashlights shine in the dark.

ELECTRIC CURRENT

Electric Current: a flow of electric charge

• Alternating Current (AC)

Alternating current is when the energy flows in different direction

• Direct Current

Direct current is when the energy flows in one direction

(Image is on the following slide)

AC AND DC

VOLTAGE

• Voltage is an electromotive force or potential difference expressed in volts

• Its measured in volts • The formula is current multiplied by

resistance

V = I x R(V= Voltage, I= Current, R= Resistance)

RESISTANCE

• Resistance slows down the flow of energy • Resistance is measured in units of ohms

(Ω)• Resistance is bigger when the pipe is

thinner and longer• Good conductors, such as copper, have

low resistance. • Poor conductors, such as iron, have

higher resistance

CELLS

• In electricity, a cell is a device that produces an electric current by converting chemical or radiant energy into electrical energy.

• Batteries are made of one or more cells

CELLS (PART 2)

Parts of a Cell• Cells contain a mixture of chemicals

called an electrolyte (allows energy to flow)

• Electrodes is the part of a cell through which charges enter or exit

• Chemical changes between the electrolyte and the electrodes convert chemical energy into electrical energy

CELLS (PART 3)

Kinds of Cells• There are two kinds of cells, wet cells and

dry cells

• Wet cells have liquid electrolytes (a car battery is made of several wet cells that use sulfuric acid as the electrolyte)

• Dry cells work in a similar way, but the electrolytes in dry cells are solid or paste like (these cells are used in small radios and flashlights)

THERMOCOUPLE

• A thermocouple is a temperature-measuring device consisting of two dissimilar conductors that contact each other at one or more spots, where a temperature differential is experienced by the different conductors (or semiconductors)

• Thermocouple is a device that converts energy into electrical energy

PHOTOCELL

• A Photocell is a solid-state device that converts light into electrical energy by producing a voltage

• Most photocells contain silicon atoms. As long as light shines on the photocell, electrons gain enough energy to move between atoms. The electrons are then able to move through a wire to provide electrical energy to power a device, such as a calculator.

ELECTRIC POWER

• Electric power is the rate at which electric energy is transferred by an electric circuit

• The SI unit of power is the watt, one joule per second.

• Electric power is usually produced by electric generators, but can also be supplied by sources such as electric batteries

WATTS

• Watt is the SI unit of power, equivalent to one joule per second

• It corresponds to the power in an electric circuit in which the potential difference is one volt and the current one ampere

• Another common unit of power is the kilowatt

• One kilowatt is equal to 1,000 W

WAYS TO SAVE ENERGY• Set your home’s thermostat a few degrees lower. For each one-

degree change, your family can save up to 5 percent on your home’s heating and cooling costs!

• Turn off lights and all electronics (like computers, televisions, stereos, and video-games) when you leave a room.

• Use the microwave instead of the oven for cooking your meals.

• Use machines like washers, dryers, and dishwashers after 8 p.m.

• Open your blinds or curtains on sunny winter days to let the sun shine into your home.

• Save hot water by taking short showers instead of baths.

• Turn off the water while you brush your teeth.

• Occasionally hold a ribbon up to the edges of your home’s windows. If air is leaking into, or out of, the house, the ribbon will move. If you find a leak, let someone in your family know so they can fix it.

THANKS FOR WATCHING!!!

HOPE YOU ENJOYED THE PRESENTATION ON

ELECTRICITY!