2-2 Electromotor (2.1)

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

Glowing, electromotor

and speakers (p. 600)

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)

- COntent (15 min)

- Jigspace (8 min)

- Working on your own 

        (12 min)

- Corrections (5 min)

- Conclusion(5 min)

                       Lesson goals:

    -  Explain how the colour changes when an object heats up. 

- Explain how an electromagnet works. 

- Explain how an electromotor works.

- Explain how a loudspeaker works.

Glowing

• At 2 500 degrees a light bulb 

        gives off white light.

• Charcoal (in a barbeque) glows read because it is not that hot.
  
• The coulours emitted as an object heats up: 
  

       red -> orange -> yellow -> white -> bluish

Electromotor (1)

• In an electromotor there are rolls of copper wire  (coil).
  
• A coil through wich a current flows

        becomes a magnet.

• When the current stops flowing, the 

        magnetic properties disappear.

• With electromagnets heavy metal plates can be moved. 
  

Electromagnet

There are two ways in which we can make an electromagnet stronger: 

- More turns of copper wire.

- Greater current.

Electromotor (2)

The two northpoles of a magnet 

repel each other.

A north and a south pole of a 

magnet will attract each other.

Electromotor (3)

• The most important components

       of an electromotor are the coil
       and a magnet. 

• Throu the coil there is a rotatble axle. 
  
• Due to the forces of attraction and repulsion
  

       of the magnet, the coil start turning.

Loudspeaker

• A loudspeaker converts current into sound. 
  
• It also contains a coil and a magnet. 
  
• The electricity flows through the coil, an thus it is attracted or repelled by the magnet. 
  
• Because the magnet starts to move 
  

the paper cone in the loudspeaker also  
moves and creates sound.

An electromagnet consists of a cool through with an electric current flows.

1. True
2. False

In your house you can find up to 10 items working with an electromagnet.

1. True
2. False

The earphones of you iPod works with a small coil.

1. True
2. False

With the colour of a light bulb, you can estimate the temperature.

1. True
2. False

When you change the direction of the current in a coil, the north- and south pole of the magnet switch sides.

1. True
2. False

Jigspace - speaker

Now do all teh questions from 

6 up to 13 (blz. 61)

WHEN YOU ARE DONE: search youtube videos on how electromotors work

RULES:

• Write in your writingbook
  



• Use: Your textbook
• No discussion
  


• In 12 minutes we will discuss the answers
  

Conclusion:

- When an electric current flows through a coil 

   then the coil becomes an electromagnet.

the more the number of turns of copper wire = stronger magnet

- If a coil (with a current passing through it) is in a magnetic field, forces are excerted on the coil and the magnet.

- This is the principle that makes an electromotor turn.