P11: Lenses and The Eye Flashcards
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Concave (Diverging) Lens
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Concave (Converging) Lens
Uses of a convex lens
Magnifying Glass, In a camera to create a clear image of a far off object.
Uses of a concave lens
To correct short sightedness.
Focal Length
The distance from the centre of a lens to where the light rays focus (or, in the case of a concave lens, appear to diverge from.)
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Real Image, from a convex lens.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/189/138/046/q_image_thumb.gif?1463388454)
Virtual Image, from a concabe lens
Magnification of an image =
Image height/ Object Height
How to construct a real image/converging lens diagram
![](https://s3.amazonaws.com/brainscape-prod/system/cm/189/138/048/a_image_thumb.jpg?1463388456)
How to construct a virtual/Converging lens diagram
![](https://s3.amazonaws.com/brainscape-prod/system/cm/189/138/049/a_image_thumb.jpg?1463388456)
How to construct a virtual/Diverging lens diagram
![](https://s3.amazonaws.com/brainscape-prod/system/cm/189/138/050/a_image_thumb.jpg?1463388457)
How does a camera work?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/189/138/051/a_image_thumb.jpg?1463388458)
What does ‘real is positive’ mean?
Real images are given positive focal lengths in the formula, virtual negative.
1/focal length =
1/distance from object to lens + 1/distance from lens to image
(1/u + 1/v = 1/f)
A diverging lens…
… always gives a virtual image.