Electricity Summary lesson

Electricity Summary lesson

Structure of the Atom

• Protons are POSITIVELY CHARGED Neutrons are NEUTRAL Electrons are NEGATIVELY CHARGED

  
  

• Overall an atom is typically neutral because the protons and electron numbers are the same and the positive and negative charges balance.

Static Electricity

Static Electricity is the build up of negative charge (electrons) when two objects that are really good insulators rub together.

- A material that gains electrons have a negative charge

- A material that loses electrons have a positive charge

Static electricity only occurs in insulating material because the charges in a conductor can move around freely, so a charge cannot build up in one place and spreads out across the surface

Multiple Choice

Define the term insulator

• A material that allows the charge to move freely

• A material that does not allow charge to move easily

Static Electricity

When a charged object comes near to another object the two objects will either attract or repel each other:

•if the charges are the same - they repel

•if the charges are opposite - they attract

•if one is charged and the other is not - they may attract depending on the nature of the substances

Like charges repel, and unlike charges attract.

Static electricity being discharged.

Multiple Choice

True or false: Static electricity only happens in materials that are insulators

• True

• False

Current Electricity

The current in a circuit depends on the potential difference and the resistance.

It is easy to think of each of these in the following way:

•the current is the flow of electric charges

•the potential difference provides the 'push‘

•the resistance restricts the flow of charges

Multiple Choice

State the unit for current

• (I)

• (A)

• (V)

• (R)

Multiple Choice

State the piece of equipment used to measure the potential difference

• Ammeter

• Voltmeter

• Newton meter

Fill in the Blanks

Two things that are required for current to flow in a circuit.

1. You require a complete circuit.

2. A power supply which “pushes” the charged particles around the circuit.

Multiple Choice

True or False: The electrons in a circuit are only found in the battery

• True

• False

Electrical Resistance

The wires and the other components in a circuit reduces the flow of charge through them. This is called resistance.

The unit of resistance is the ohm, and it has the symbol Ω (an uppercase Greek letter omega

What causes resistance?

When electrons move through the wire, some electrons collide with the ions of the material in the wire. It is these collisions that cause electrical resistance. With each collision, some energy is lost to the wire as heat. This explains the heating effect of current.

What happens to the current if the resistance increase? 

•Increasing the resistance decreases the current. You can increase the resistance by adding more components with higher resistance.

What happens to the current if the potential difference increases? 

. The greater the battery voltage (i.e., electric potential difference), the greater the current.

Multiple Choice

State where an ammeter should be placed in a circuit

• In series

• Parallel to the component

Multiple Choice

State where a Volt meter is placed in a circuit

• In series

• Parallel to the component it is measuring

Series Circuits

• if a lamp breaks or a component is disconnected, the circuit is broken and all the components stop working.

• The current is the same everywhere in a series circuit. It does not matter where you put the ammeter

• If you put more lamps into a series circuit, the lamps will be dimmer than before because less current will flow through them.

Parallel Circuits

• In a parallel circuit, different components are connected on different branches of the wire

• If a lamp breaks or a component is disconnected from one parallel wire, the components on different branches keep working.

• When two components are connected in parallel, the current is shared between the components. The current is shared when it reaches the branches, then adds again where the branches meet

Multiple Choice

State what happens to the current in a series circuit

• The current is the same throughout the circuit

• The current is shared between the components

Explain the function of a fuse in ensuring electrical safety

• A fuse provides a built-in fail-safe to the electrical circuit for a device. The fuse contains a thin wire that will melt if the current gets too high. 

• Once the fuse has melted, the circuit is broken and no more current flows through the device. This means the case of the device is no longer live and there is no more risk of electrocution

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Now: Complete the quiz on google classroom, it should take 25-30 minutes

. Have a go at every question

. Do NOT leave any questions blank

. If you need any help, ask

. Answer in FULL sentences