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17 Mar 2010 11:03:43 IST

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how we can take the sign convension in the converging lens

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how we can take the sign convension in the converging lens

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Dasvidaniya

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17 Mar 2010 11:14:40 IST

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Following sign convention is used r measuring various distances:

All distances on the principal axis are measured from the optical centre.
The distances measured in the direction of incident rays are positive and all the distances measured in the direction opposite to that of the incident rays are negative.
All distances measured above the principal axis are positive. Thus, height of an object and that of an erect image are positive and all distances measured below the principal axis are negative.

Note:

The rules are same as in case of spherical mirrors.

The following table gives the sign convention for lenses:

Types of lens	U	v		f		Height of the image		Height of the object
Types of lens	U	Real	Virtual	Real	Virtual	Real	Virtual	Height of the object
Convex	-	+	-	+	No virtual focus	-	+	+
Concave	-	No real image is formed	-	No real focus	-	No real image is formed

Vaibhav

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20 Mar 2010 12:41:59 IST

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Always use f= +ve in case of converging lens and f= -ve in case of diverging lens

pradeep rout

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29 Mar 2010 10:22:59 IST

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for taking sign for v , u and f if the distance from the the pole is in the direction of the incident ray then the sign is +ve but if it is opposite to the direction of the incident ay then it is taken - ve.( u is always -ve)

for image and object if the image is on the same side of the principal axis in which the object is then it is + ve otherwise -ve .

edison

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Joined: 19 Oct 2006

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22 Jun 2011 18:18:34 IST

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http://www.tutorvista.com/content/science/science-ii/refraction-light/sign-lenses.php

http://www.tutorvista.com/physics/sign-convention-for-lenses

http://en.wikipedia.org/wiki/Lens_(optics)

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