Difference between revisions of "Convex Lens"
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: The [[Focal Length|focal length]] of a '''convex lens''' is the distance between the [[Focal Point|focal point]] and the centre of the [[lens]]. | : 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]]. | ||
Revision as of 10:26, 24 February 2019
Contents
Key Stage 3
Meaning
A convex lens is a shaped piece of glass that is thickest at the centre and thinnest at the edges.
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| A picture of a convex lens. | They symbol used in diagrams to represent a convex lens |
About Convex Lenses
- A convex lens causes parallel rays of light to converge, so it can also be called a converging lens.
- A convex lens is used to focus light.
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| A convex lens focuses parallel rays to a focal point. |
Key Stage 4 Higher
Meaning
A convex lens is a shaped piece of glass that is thickest at the centre and thinnest at the edges.
|
|
| A picture of a convex lens. | They symbol used in diagrams to represent a convex lens |
About Convex Lenses
- A convex lens causes parallel rays of light to converge, so it can also be called a converging lens.
- A convex lens is used to focus light.
Finding the Focal Length
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| 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.