| Question |
Answer |
| Define power for a lens? | Power=1/focal length |
| What is the unit for power of a lens? | Dioptre, D |
| What is the lens formula? | 1/f = 1/u + 1/v |
| What kind of image is formed from a converging lens, when the object-to-lens distance is smaller than the focal length? | Virtual image |
| What are the differences between a real and virtual image? | A real image is inverted and can be formed on a screen, whereas virtual images are upright and cannot be formed on a screen. |
| For a converging lens, where must the object be placed to give a real image of the same size as the object? | At u=2f
because using: 1/f = 1/u + 1/v
when object-size=image-size, u must equal v
so you get 1/f = 1/u + 1/u = 2/u
therefore u = 2f
|
Cardio Block2anatomy
