Difference between revisions of "Focal Length"
(Created page with "==Key Stage 4 Higher== ===Meaning=== The '''focal length''' of a lens is the distance between the lens and the focussed image of a "distant object". ===Ab...") |
|||
| Line 22: | Line 22: | ||
: The [[Image Distance|image distance]] (the distance between the [[focus]]sed [[image]] and the [[lens]]) is the same as the [[Focal Length|focal length]] for a "distant object". | : The [[Image Distance|image distance]] (the distance between the [[focus]]sed [[image]] and the [[lens]]) is the same as the [[Focal Length|focal length]] for a "distant object". | ||
: If the [[Object Distance|object distance]] (the distance between an [[object]] and a [[lens]]) is too small, then the [[Focal Length|focal length]] is not the same as the [[Image Distance|image distance]]. | : If the [[Object Distance|object distance]] (the distance between an [[object]] and a [[lens]]) is too small, then the [[Focal Length|focal length]] is not the same as the [[Image Distance|image distance]]. | ||
| + | |||
| + | ===References=== | ||
| + | ====AQA==== | ||
| + | |||
| + | :[https://www.amazon.co.uk/gp/product/1471851370/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851370&linkCode=as2&tag=nrjc-21&linkId=01c69b0ae058f809cf636033e6ba793e ''Focal length, page 204, GCSE Physics, Hodder, AQA ''] | ||
| + | :[https://www.amazon.co.uk/gp/product/178294558X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=178294558X&linkCode=as2&tag=nrjc-21&linkId=f0dfb66dafcb0c6e9449e7b1a4ae1ac178 ''Focal length, page 82, GCSE Physics; The Revision Guide, CGP, AQA ''] | ||
| + | :[https://www.amazon.co.uk/gp/product/019835939X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=019835939X&linkCode=as2&tag=nrjc-21&linkId=57e96876985fc39b1a3d8a3e3dc238b6 ''Focal length, pages 208-211, GCSE Physics; Third Edition, Oxford University Press, AQA ''] | ||
| + | :[https://www.amazon.co.uk/gp/product/1782945970/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945970&linkCode=as2&tag=nrjc-21&linkId=a120d24dcc7cc7a58192069a3aafc1d2 ''Focal length, pages 266, 267, 272, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA ''] | ||
Revision as of 16:18, 15 November 2019
Key Stage 4 Higher
Meaning
The focal length of a lens is the distance between the lens and the focussed image of a "distant object".
About Focal Length
 |
| A convex lens focuses parallel rays to a focal point. |
- The focal length of a convex lens is the distance between the focal point and the centre of the lens.
 |
| A diagram showing how to find the focal length of a convex lens. |
To find the Focal Length of a convex lens:
- Focus the image of a "distant object" onto a screen.
- Measure the distance between the lens and the screen.
- The image distance (the distance between the focussed image and the lens) is the same as the focal length for a "distant object".
- If the object distance (the distance between an object and a lens) is too small, then the focal length is not the same as the image distance.