Solutions: Medical Option - the EYE
Q10.
(a) The diverging lens in the figure below forms an image of the object.
![](ediagram10ans.png)
Complete the figure by drawing a ray diagram to show the formation of the image. Label the image.
- ray diverging from F
![](../../../../graphics/symbols/nuclides/ticksmall.png)
- ray through centre of lens to form labelled image
![](../../../../graphics/symbols/nuclides/ticksmall.png)
(2 marks)
(b) A diverging spectacle lens of power –3.0 D is used to correct a defect of vision. When used to view a real object, the image is formed 0.21 m from the lens.
(i) State the defect of vision.
Myopia or short sight ![](../../../../graphics/symbols/nuclides/ticksmall.png)
(ii) Calculate the distance of the object from the lens.
P = 1/f = 1/u + 1/v
-3.0 = 1/u - 1/0.21 ![](../../../../graphics/symbols/nuclides/ticksmall.png)
1/u = 1/0.21 - 3.0 = 1.76
u = 0.57 m ![](../../../../graphics/symbols/nuclides/ticksmall.png)
(3 marks)
(Total 5 marks)