3T Electricity Summary

• Natuurkunde
• Middelbare school
• vwo
• Leerjaar 3

Electricity

Summary

Welcome!

Plan for today

1. Questions

2. Summary or self study

3. Self study

        - Do the 'test yourself'

        - Study the paragraphs (summary + definitions: p. 60-63)

        - Work on the diagnostic test

        - Work on problems in the book

Do you already have some questions?

What parts do you find most difficult?

§1 - The power station

§1 - Induced voltage

§1 - Electrical power

Electrical power is just the energy that something uses per second! So we calculate it with:

P=​t​​E​​

Special units:

W       -     J       -    s

kW  -  kWh    -      h

1 kWh = 3.600.000 J

§2 - The energy grid

!!!

At home: 

U = 230 V

§2 - The transformer

Every transformer:

Ideal transformers:

​U​s​​​​U​p​​​​=​N​s​​​​N​p​​​​

P​p​​=P​s​​

§2 - Capacity

Every battery has a certain capacity. The capacity tells you how long a battery can deliver a certain current. You can calculate it with:

C=I⋅t

Special units:

Ah       -     A       -    h

mAh     -  mA    -    h

§3 - Voltage & Current

U​tot​​=U​1​​=U​2​​=...=230V

I​tot​​=I​1​​+I​2​​+...

§3 - Wires & Colours

§3 - Electrical power

We can find a relation between the electrical power of a device, the current running through that device and the voltage that it is connected to:

P=U⋅I

Multiple devices at home:

P​tot​​=U⋅I​tot​​

§4 - Dangers of electricity

• The current through the wires gets too high                                                                 --> Danger of fire!                                                                    Caused by overloading or short-circuiting                                                                                                           
• Current from a wire can run through your body                                          --> Can be deadly above 1A! (see table 1)                                                        Caused by loose or broken wires 

§4 - Prevention high current

Fuses

A fuse blows if the current gets too high.

Circuit breakers

Flips and stops current in one group.

§4 - Prevention getting shocked

Earth leakage circuit breakers

Earthing

Double isolation