Electricity

Electricity

Technology 3º ESO

​What is electricity?

Matter is formed by atoms consisting of negatively charged particles (electrons) and positively charged particles (protons). Between these particles, there are forces of attraction or repulsion that generate a type of energy called electricity.

If an atom has the same number of electrons as protons, will it be balanced or un-balanced?​

What is electricity?

​What is electricity?

When an atom has electrons=protons it's called STABLE ATOM.

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- A stable atom has the same number of electrons than protons and it has no charge.

· If an atom has more electrons than protons it has Negative charge

· If an atom has fewer electrons it has Positive charge.​

...so...​

...we can define electricity as a flow of electrons in a substance.​

What is electricity?

​How does a cell/battery works?

The battery needs an electrical circuit to get up and running and generate chemical reactions. 

These reactions are what allow the battery to fulfill its function of powering an electrical device, but what do these reactions consist of?

1. Inside the battery is a liquid called electrolyte.

2. There are 2 poles, called electrodes, and when each one is immersed in the electrolyte it generates a different reaction:

How does a cell/battery works?

​How does a cell/battery works?

a) The negative pole (Cathode) is reduced, releasing electrons in that reaction.

b) The positive pole (Anode) is oxidized, collecting the electrons released by the other pole.

As you will see when you build your box the electrical circuit closes once all the elements are connected.The circuit formed by a battery, cables, bulb and / or motor is the simplest circuit.

How does a cell/battery works?

​Electric circuit

An electric circuit is a closed path of interconnected elements.

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

What is a electric circuit?

​Electric current

The movement of electons in the same direction is called electric current.

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A good simil to understand electricity is to compare it with a flow of water.​

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What is electric current?

​Electric current concepts

Electricity is the movement of electrons along an electrical conducting material.

The electrons move from an atom to the next according to this picture.

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​Voltage (V)

It's the force that makes electricity move through a wire.

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It's measured in Volts (V)

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​Electric current variables (magnitudes)

Explain everything you know about the electric current.

Current (I)

It's the number of electrons that travel through a point in a second. 

So, it's the charge flow trough an element. It's measured in Amperes or Amps (A).

An Amp means 6.241.000.000.000.000.000.000 electrons per second.​

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​Electric current variables (magnitudes)

Explain everything you know about the electric current.

​Resistance (R)

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It's the variable that tells us the opposition to the flow of an electric current.

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It's measured in Ohm (Ω).

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​Electric current variables (magnitudes)

Explain everything you know about the electric current.

​There are a big amount of different circuits but all of them are created from the two basic types that are parallel and series circuits.

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​Types of electric circuit

What different types of electric circuits do yo know?

​There are a big amount of different circuits but all of them are created from the two basic types that are parallel and series circuits.

A series circuit is a closed circuit in which the current follows one path, as opposed to a parallel circuit where the circuit is divided into two or more paths.

In a series circuit, the current through each load is the same and the total voltage across the circuit is the sum of the voltages across each load. 

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​Series circuit

Explain everything you know about a series circuit.

In a series circuit, the total resistance is equal to the sum of the individual resistances.

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​Series circuit

What is a series circuit?

​A parallel circuit is a closed circuit in which the current divides into two or more paths before recombining to complete the circuit.

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Each load connected in a separate path receives the full circuit voltage, and the total circuit current is equal to the sum of the individual branch currents. 

Parallel circuit

Explain everything you know about a parallel circuit.

In this case, the total resistance/inductance is equal to the reciprocal of the sum of the reciprocals of their individual resistances/inductances: 1/Rt=1/R1+1/R2+1/R3... 

​(note: the total resistance will always be less than any individual resistance)..

Parallel circuit

What is a parallel circuit?

Electric circuit element

Draw and name different circuit elements.

Cell

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Switch

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Push button switch​

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​Lamp/Bulb

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Heating elements​

Motor

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Buzzer / Electric bell

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Speaker

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​Voltmeter

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Ammeter​