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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..."
==Key Stage 4 Higher==
===Meaning===
The '''focal length''' of a [[lens]] is the [[distance]] between the [[lens]] and the [[focus]]sed [[image]] of a "distant object".
===About Focal Length===
{| class="wikitable"
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|[[File:ConvexLensFocalPoint.png|center|500px]]
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| style="height:20px; width:200px; text-align:center;" |A '''convex lens''' [[focus|focuses]] [[parallel]] [[Light Ray|rays]] to a [[Focal Point|focal point]].
|}
: The [[Focal Length|focal length]] of a '''convex lens''' is the distance between the [[Focal Point|focal point]] and the centre of the [[lens]].
{| class="wikitable"
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|[[File:FocalLength.png|center|500px]]
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| style="height:20px; width:200px; text-align:center;" |A [[diagram]] showing how to find the [[Focal Length|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|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]].
===Meaning===
The '''focal length''' of a [[lens]] is the [[distance]] between the [[lens]] and the [[focus]]sed [[image]] of a "distant object".
===About Focal Length===
{| class="wikitable"
|-
|[[File:ConvexLensFocalPoint.png|center|500px]]
|-
| style="height:20px; width:200px; text-align:center;" |A '''convex lens''' [[focus|focuses]] [[parallel]] [[Light Ray|rays]] to a [[Focal Point|focal point]].
|}
: The [[Focal Length|focal length]] of a '''convex lens''' is the distance between the [[Focal Point|focal point]] and the centre of the [[lens]].
{| class="wikitable"
|-
|[[File:FocalLength.png|center|500px]]
|-
| style="height:20px; width:200px; text-align:center;" |A [[diagram]] showing how to find the [[Focal Length|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|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]].