UNIT 4_ Electricity

Technologies 1 ESO

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WORKSHEET 1

INTRODUCTION TO ELECTRICITY

REVIEW QUESTIONS:1.- What are the names of the particles that form the atom?2.- What is electricity?3.- What type of energy do we store into batteries?4.- From which to which battery terminal do the electrons

flow?5.- What is a circuit?6.- What happens if a bulb connected in parallel with another

bulb, breaks?

WHAT DO WE USE ELECTRICITY FOR?

Applications of electricity…

Electricity is something that we don’t use directly. To use electrical energy, we first need to transform it into a different type of energy.

(Worksheet 2 activity 1)

BELL: Electrical E. Acoustic E. (sound)

RESISTOR: Electrical E. Thermal E. (heat)

BULB / LAMP: Electrical E. Luminiscent E. (light)

ENGINE / MOTOR: Electrical E. Kinetic E. (rotatory movement)

WHAT IS ELECTRICITY?Electricity is the movement of electrons along an

electrical conducting material.

ELECTRON (-)

NEUTRON PROTON (+)

CONDUCTING MATERIAL

Electron that leaves the atom

Movement of electrons

The electron leaves a space in its atom that is occupied by the next electron(Worksheet 2

activity 2)

THE ELECTRIC CURRENTThe movement of electrons in the same direction is

called electric current. It goes from the positive terminal of the battery to the negative.

Direction of electrons

Direction of the electric current

Something you need to learn…

ELECTRIC CIRCUITSAn electric circuit is a closed path of interconnected

elements. This path allows the electric to flow. The function of a circuit is to transform electricity in a useful type of energy.

ELEMENTS OF CIRCUITSNECESSARY ELEMENTS

TYPE OF ELEMENT FUNCTION EXAMPLES

Generators To suply the circuit with energy BatteryPhotovoltaic generator (solar pannels)

Conductors To connect the elements among them Cables (wires): made of copper, steel, aluminum…

Receptors To transform the electric energy into a useful type of energy

Motor / Engine (kinetic energy)Bulb / Lamp (luminiscent energy)Bell (acoustic energy)Resistor(thermal energy)

COMPLEMENTARY ELEMENTSTYPE OF ELEMENT FUNCTION EXAMPLES

Control elements To control the flow of energy along the circuit

SwitchPush buttonCommutator

Protection elements To protect the circuit and / or its usersFuseDifferential

(Worksheet 2 activity 3)

GRAPHIC REPRESENTATION OF CIRCUITS

We represent circuits in an easy, standardized and graphic way. The objective is that everyone can understand our circuits. It’s also faster and easier to draw.

We use these standardized symbols:

Battery

Switch

Push button

Motor / Engine

Lamp / Bulb Resistor

Bell

GRAPHIC REPRESENTATION OF CIRCUITS (II)

(Worksheet 2

activity 4)

TYPES OF CIRCUITS

WORKSHEET 3

ELECTRICAL VARIABLESThere are 3 essential variables in a circuit:-Voltage-Current-Resistance

VOLTAGE (V) is the force that makes electricity move through a wire. It’s measured in Volts (V).

Between two points in a circuit, there is a difference in electric potential: that difference is voltage.

ELECTRICAL VARIABLES (II)CURRENT (I) is the number of

electrons that travel through a point in a second. So, it’s the charge flow through an element. It’s measured in Amperes or Amps (A).

Curiosity: an Amp means 6.241.000.000.000.000.000.000 electrons per second.

Current

ELECTRICAL VARIABLES (III)

RESISTANCE (R) is a material’s tendency to resist the flow of charge. It’s measured in Ohms (Ω).

Receptors and conductors have a certain resistance that makes the electrons lose energy.

ELECTRICAL VARIABLES (IV)These essential variables allow us to compare an electrical

circuit and a water circuit.

OHM’S LAW

V = I · RIf voltage is increased

and resistance remains the same, the current will increase.

If resistance is increased and voltage remains the same, the current will decrease.

The three electrical variables are related between them by a law that was defined by the German scientist George S. Ohm in 1.826:

OHM’S LAW (II)To deduce the different values of

the three variables, we can use the Ohm’s triangle.

WORKSHEET 4