# Lesson 6 — 6.4 + 6.5

Science P4

The speed of light
&
Reflection
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Slide 1: Tekstslide
Speed of light + reflectionMiddelbare schoolhavo, vwoLeerjaar 2

In deze les zitten 28 slides, met tekstslides en 1 video.

## Onderdelen in deze les

Science P4

The speed of light
&
Reflection

#### Slide 1 -Tekstslide

This lesson
• Completing the speed of light
• Reflection — Phet simulation
• The practical

#### Slide 2 -Tekstslide

Learning goals
• Name the speed of light and it's name in physics
• Explain how the speed of light us used as a unit of distance
•  Explain how astronomers use light to study space
•  Be able to do calculations using the speed of light

#### Slide 3 -Tekstslide

• During class – have a question, raise your hand.

• When working  together, do not talk with or shout to people on the other side of the class.

• While working independently, do not disturb the class.

•  Participate seriously in the class (also when working with our phones). do not make noise, inappropriate jokes, chat with everyone around you, shout through the class, etc.

• After one warning, when you break the rules again— You go to olc 2 with extra work.

#### Slide 4 -Tekstslide

Recap
Speed of light

What did we learn about the speed of light?

#### Slide 5 -Tekstslide

what is the speed of light?

300 000 000 m/s
Of  300 000 km/s

#### Slide 7 -Tekstslide

What is the symbol for the speed of light?

c
'Celerity'
Latin for Swift

#### Slide 9 -Tekstslide

In astronomy light is used as a unit of...

Distance
Light years

#### Slide 11 -Tekstslide

Measuring the speed of light

#### Slide 12 -Tekstslide

Calculations with the speed of light

#### Slide 13 -Tekstslide

Calculate how long it would take in minutes for light to travel from the Sun to the Earth in.

#### Slide 14 -Tekstslide

Given
• Speed of light = c = 300 000 000 m/s = 300 000 km/s
• Distance = 150 000 000 km

• How long does it take for light of the sun to reach the Earth.

Formula
• v = d/t        t = d/v

Calculation
• t = 150 000 000 / 300 000 = 500s
• 500s / 60 = 8.3 minutes (8 minutes and 18 seconds)

#### Slide 15 -Tekstslide

Exercise
The closest star to our sun is Proxima Centauri. This star is 40,208,000,000,000 km away from our sun.

The speed of light is 9 460 000 000 000 kilometers per year.

How many light years away is Proxima Centauri from our sun?

#### Slide 16 -Tekstslide

Given
• Speed of light in km/year = 9 460 000 000 000
• distance proxima centauri Earth = 40 208 000 000 000

• How many light years away is Proxima Centauri?

Formula
• -

Calculation
40 208 000 000 000/ 9 460 000 000 000 = 4.2 light years

#### Slide 17 -Tekstslide

• The speed of light = 300 000 000 m/s — called 'c' in physics.

• Light is used as a measure of distance (light years).

• Astronomy studies the universe through the information in the light that reaches earth.

• to measure the speed of light, technology had to invented that measures time in small enough intervals to be able to detect it.

• calculations using the speed of light

6.4 Reflection

#### Slide 19 -Tekstslide

• Plane mirror
• Image
• Virtual image — Real image
• Types of reflection
• The law of reflection
•  Incident ray — reflected ray
• Angle of reflection

#### Slide 21 -Tekstslide

Phet simulation
• Search for: Phet bending Light
• Experiment with this independently for 5 minutes
• What can you learn about reflection? Find out as much as you can
• Write down what you learned

#### Slide 22 -Tekstslide

law of reflection

#### Slide 25 -Video

Homework
Do: Workbook exercises 6.4 (Including E)

#### Slide 26 -Tekstslide

The electromagnetism practical

#### Slide 27 -Tekstslide

Learning goals
• Name the speed of light and it's name in physics
• Explain how the speed of light us used as a unit of distance
•  Explain how astronomers use light to study space
•  Be able to do calculations using the speed of light