2-1 Introduction electricity (p2.1)

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

What can you do 

with electricity?

(blz. 57)

What you need:

- Textbook, writingbook, iPad

- Pen, pencil, geotriangle

Schoolbags in the cuboard

Phones in the phonebag

Bluetooth 

- ON

- VPN off

    Lesson today:

- Test discussion (10 min)

- Discuss building project 

        (5 min)

- Lesson goals (2 min)

- Content (15 min)

- Work by yourself 

      (10 min)

- Corrections (5 min)

- Conclusion (2 min)

Building project (over 4 weeks)

- Electromagnet (not to hard) maximum of 7

- Electromotor (relatively hard) maximum 10

- Generator (difficult) maximum 10

- Speaker (Difficult) maximum 10

P. 65 in your textbook

                       Lesson goals:

- Explain the terms: Electric current, electromagnet and electromotor. 

- Name and explain a few applications of electricity.

p. 55

Group discussion of questions

Heating using electricity

With a very high current, conducting wires heat up, and this can be a fire hazard. 

E.g. a weldingmachine joins two pieces of metal at a temperature of  3 000 ^oC.

Light

The filament in a lightbulb reaches 2 500 ^oC

- Lightbulb glows with white light

- Energyloss: We want light and not heat

Neon or sodium lamps (streetlanterns) dont get as hot. 

The colour of light depends on the gas in the tube. 

Fluorescent tubing produces white light because of a special powder coating inside the tube.

Light fluorescent tubing

A fluorecent tube works by generating ultraviolet light in a mercury discharge. Phosphor powder coated on the inside of the tube uses the energy of the UV light to give off its own light, white light. 

Light  LED

LED (light emitting diode) - does not work with a gas, but with a semi conductor.

It is a metal like substance in a 

material (diode).

The colour of the LED depends 

on the type of semi conductor

Want more: google 'how does a LED work'.

Light LCD-screens

LCD-screens (liquid crystal display)

- They contain tiny liquid crystals. 

- The crystals dont give off light 

    themselves but allows certain 

    colours of light, that are emitted

    behind them, to pass through.

- There are seperate crystals for red, green and blue light. 

Light Plasma-tv

A plasma TV is made of small dots that emit red, green or blue light.Each dot is like a small fluoreschent tube.

Moving with electricity 

You can also make motion 

with electricity, usually an electromotor.

These electromotors are used in 

many toys, but also in trains, electric and hybrid cars, and lifts.

How hot does the filament of a lightbulb get?

1. 100
2. 500
3. 2 500
4. 3 000

Which light source is not energy efficient?

1. Neon lamp
2. Fluorescent tubing
3. filament light bulb
4. Sodium lamp

What determines the colour of light in a fluorescent tube?

1. Gas
2. Material of filament
3. Powder

The Crystals in a LCD screen do not emit their own light.

1. True
2. False

The working of a plasma TV can be compared to that of fluorescent tubing.

1. True
2. False

Bright light that is emitteer when welding comes from the extremely hot metal.

1. True
2. False

When a wassing machine turns, the conducting wies heat up a bit.

1. True
2. False

A LED gives light, because a metal like material conducts electricity.

1. Waar
2. Niet waar

Maak opgaven 2 t/m 4 (blz. 59)

ALS JE KLAAR BENT: zoek 'hoe werkt elektriciteit' op youtube

REGELS:

• Zelf schrijven in je schrift
  



• Hulp: je boek
• Geen overleg
  


• Over 10 minuten bespreken we de opgaven
  

Now do  2, 3 and 4 (p. 59)

WHEN YOU ARE DONE: google 'how does electricity work'

RULES:

• Write in your writingbook
  



• Use: Your textbook
• No discussion
  


• In ... minutes we will discuss the answers
  

Conclusion:

There are three application of electricity:

    - Heating

    - Giving light

    - Motion

• A fluorescent tube and an energy-saving lightbulb contain a gas that gives off UV light, and this allows the powder coting to give off white light. 
  
• A LED light contains a metal like substance that gives off light.
  
• LCD-crystal is a transparent crystal that blocks certain colours of light with electricity.