1-8 Law of reflection (1.3)

• Natuurkunde
• Middelbare school
• havo
• Leerjaar 2

Law of reflection (p. 38)

Bluetooth 

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Stationary

- Books

- Pen and pencil

- RULER

- iPad

Report

- NO

Lessonup

- Yes

Bags in

the cuboard

Phones in the phone holder

Lesson goals:

• Explain what is meant with the terms, the normal and the law of reflection. 
  

In terms of skills you should be able to:

• Draw reflected lightrays:

          (a) using the mirror image and 

          (b) using the law of reflection

Important words with constructions

Angle of incidence - angle between 

the incomming ray and the normal

Angle of reflection - angle between

the reflected light ray and the normal 

Normal - an imaginary line 

perpendicular (90 degrees) to the 

mirror surface.

Activity

1. Let the lightrays fall on your mirror. 
2. Draw the incomming and reflected lightrays. 
3. Draw the normal.
4. Measure the angle of incidence, and the angle of reflection. 
5. See if there is a relation between these two angles.

Worst case scenario: 

https://phet.colorado.edu/sims/html/bending-light/latest/bending-light_en.html

phet.colorado.edu

Law of reflection

A lightray that falls on a 

mirror reflects back with 

the same angle.

angle i = angle r

Draw the field of view

with the law of reflection

Draw the field of view

with the 

      mirror image

Constructions

Two methods to draw the reflected light rays:

1. With the mirror image
2. With the law of reflection

Example (both methods)

Steps for drawing a mirror image using the law of reflection

1. Draw a lightray (solid line)
2. Draw the normal (dotted line)
3. Draw the reflected lightray with the angle of reflection = angle of incidence
4. Extend the lightray back behind the mirror with a ditted line
5. Repeat steps 1-4 with a second lightray
6. Draw the mirror image.

Do the following questions:

46 up to 48 (p. 39)

In your writingbook

Rules: 

- 5 minutes

- No talking

Finished early: google 'how to draw a mirror image'

In a nutshell:

• Normal - imaginary line perpendicular to the surface
• Angle of incidence - angle between the incomming light ray and the normal
• Angle of reflection - angle 

       between the reflected light ray
       and the normal

• Law of reflection - angle of incidence = angle of reflection