Unformatted text preview: Sign Conventions \ 1. Mirrors. Convex and concave Usually the polished side is the from of the'mirror. However, the E where the Rays are incident on the mirror is called
the front. Ifthe object isat the front p is +ve.
If the object is at the back p is ——ve.
Ifthe image is at the front i is +ve.
If the image is at the back i is —ve.
' If the centre of curvatuie is at the from R is +ve.
If the centre of curvature is at the back R IS —ve. f: R/2.
1 1 2 1' 1 1
— + — = —— or — + — = ——
p I R p l f
2. Curved Refracting surfaces. Single curved refractin g surface [1+ ﬂ=(’72 w)
p i R 11, is the index of refraction of the medium where the object 18. n2 is the other medium The side Where the Rays are
incident on the lens is called the front.  ' I If the object is at the front p is +ve. Ifthe object is at the back p is —ve. If the image is at the back i is +ve. If the image is at the front 1 is —ve , If the centre of curvature is at the back R IS +_ve , _
If the centre of curvature is at the front R is —ve. 3. Lenses Lens maker’s equation a ﬂ: _ Li __.__. 7 A if —
p+i (n2 ”rig R2] . The side where the Rays are incident on the lens is said to be the front.
The other side of the lens is said to be the back. If the object is at the front p is +ve. . Ifthe object is at the back p is —ve. Ifthe image is at the back i is +ve. lfthe image is at the front i is ~ve. If the centre of curvature of any curved surface is at the back R is +ve. If the centre is at the front R is —ve.. i.e. For a double convex lens
Here p is +ve R] is +ve. R2 is —ve ...
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 Spring '08
 MOHAMED
 Physics

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