2-4 Different power sources (2.2)

• Natuurkunde
• Middelbare school
• havo, vwo
• Leerjaar 2

Different power 

sources (p. 66)

What you need:

- Textbook, writingbook, iPad

- Pen, pencil, geotriangle

- Calculator

Schoolbags in the cuboard

Phones in the phonebag

Bluetooth 

- ON

- VPN off

    Lesson today:

- Lesson goals (5 min)

- Group discussion (5 min)

- Content (12 min)

- Video dynamo (3 min)

- Working by yourself 

       (15 min)

- Discuss activities (7 min)

- Conclusion (3 min)

                       Lesson goals:

- Explain what the voltage is on 

    our electric network. 

- The difference between direct   

   current and alternating current.

- Explain how batteries, dynamo's 

   and solar cells work.

Discovery (p. 66)

Questions 1 up to 4 (not 9) discus in your group

The correct voltage

Electricity in the socket comes from:

- Power stations

- Wind turbines

- Solar cells

These are all examples 

Voltage

• Light bulb: 230 V
  

       Torch: 4,5 V

• Volt = the voltage of electricity, unit V
  
• A lamp made for 4,5 V burns weak on 3V and breaks at a voltage of above 4,5 V
  
• A high voltage is more dangerous than a low voltage, higher than 100 V can be fatal.
  

Alternating current and direct current

Direct current: A battery has a 

+ and a - symbol and provides DC

Alternating current: In a wall socket 

the + and - poles alternate rapidly.

Appliances made for alternaitng current dont work on direct current. 

Bicycle dynamo delivers alternating current.

Batteries

• At the + and - pole, different chemical reactions take place. 
  
• Substances are converted into different substances. 
  
• This is how a potential difference is 

        induced accross the poles of the 

        battery. 

• When it is connected in a closed 

        circuit a current starts flowing. 

Some things to know...

• If the battery is empty, the substances (reactants) are finished. 
  
• The 1,5 volt alkaline batteris are used most often. 
  
• Rechargeable batteries have a voltage of just under 1,5 V. 
  
• A batterypack or accumulator is made up of more than one rechargeable batteries or cells.

Dynamo

• It exists of an axle, coil and magnets, like an electromotor.
• The axle turns, and the coil moves past the magnets and produces an electric current. 


• It produces alternating current
• Bicycle dynamo is brighter when 
• you cycle faster - due to a greater voltage.
• A power station has a very big dynamo 

        (generator)

Solar cells:

• Direct current, expensive, lasts decades.
• You need to convert direct current to alternating current.

All batteries provide a voltage of 1,5 V.

1. True
2. False

A battery is a chemical power source.

1. True
2. False

Batteries provide direct current.

1. True
2. False

Rechargeable batteries have the same voltage as non-rechargeable batteries.

1. True
2. False

There is a large dynamo in a wind turbine.

1. True
2. False

A coil and magnet is present in a dynamo.

1. True
2. False

Direct current is not dangerous.

1. True
2. False

Now do  19 up to 27 (p. 70)

WHEN YOU ARE DONE: 

RULES:

• Write in your writingbook
  



• Use: Your textbook
• No discussion
  


• In 10 minutes we will discuss the answers
  

Conclusion

- Electricity is provided by a power 

    source.

- Electrical appliances must be connected to the right voltage. 

- With direct current the current only flows in one direction, and with alternating current the direction of the current changes consistently. 

- A battery provides direct current and a dynamo provides alternating current.