Vwo 3, Lens equation + Magnification

• Natuurkunde / Scheikunde
• Middelbare school
• vwo
• Leerjaar 3

Chapter 3, Light and lenses

Paragraph 3, Cameras and projectors

Today

- Live lesson + lessonup

- Recap paragraph 2

- exercise 18,19 and 20 together

- Continuation paragraph 3

Recap

Some questions about paragraph 2 will follow

Paragraph 2 was about:

A positive lens is:

1. Convergent
2. Divergent

A positive lens:

1. deflects rays of light outward
2. reflects rays of light back
3. deflects rays of light inward

A negative lens is:

1. Convergent
2. Divergent

A negative lens:

1. deflects rays of light inward
2. reflects rays of light back
3. deflects rays of light outward

After passing a positive lens, the rays of light converge and meet at one point, called:

1. the point
2. the focal point
3. the burning point
4. the vocal point

With how many construction rays do you draw an image?

1. 2
2. 3
3. 1
4. 4

Take a picture of your answer from worksheet 3-5

Take a picture of your aswer from worsheet 3-6

Take a picture of your aswer from worsheet 3-7

Paragraph 3, cameras and projectors

In the following question match 

the 'distance' with its position

Object distance

Image distance

Focal distance

Paragraph 3, Cameras and projectors

object distance = u

image distance = v

focal distance = f

Paragraph 3, Cameras and projectors

Lens equation

u = object distance

v = image distance

f = focal distance

​f​​1​​=​u​​1​​+​v​​1​​

Paragraph 3, Cameras and projectors

                                                                                        f = 2 cm

                                                                                        v = 5 cm

                               u  = 1 / (1 / 2 - 1 / 5 ) = 3,33 cm

​f​​1​​=​u​​1​​+​v​​1​​

​u​​1​​=​f​​1​​−​v​​1​​

​u​​1​​=​2​​1​​−​5​​1​​

An object is positioned 5 cm behind a positive lens (f = 3 cm).
Calculate the image distance to 1 decimal.

An object is positioned 4 cm behind a positive lens (f = 3 cm).
Calculate the image distance to 1 decimal.

An object is positioned 4 cm behind a positive lens (f = 3 cm).
Calculate the image distance to 1 decimal.

An object is positioned 10 cm behind a positive lens. The sharp image is visible at 15 cm on
the other side of the lens.
Calculate the focal length.