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Key Equations

Image distance in a plane mirror do=−dido=−di
Focal length for a spherical mirror f=R2f=R2
Mirror equation 1do+1di=1f1do+1di=1f
Magnification of a spherical mirror m=hiho=−didom=hiho=−dido
Sign convention for mirrors
Focal length f +for concave mirror−for convex mirror+for concave mirror−for convex mirror
Object distance do +for real object−for virtual object+for real object−for virtual object
Image distance di +for real image−for virtual image+for real image−for virtual image
Magnification m +for upright image−for inverted image+for upright image−for inverted image
Apparent depth equation hi=(n2n1)hohi=(n2n1)ho
Spherical interface equation n1do+n2di=n2−n1Rn1do+n2di=n2−n1R
The thin-lens equation 1do+1di=1f1do+1di=1f
The lens maker’s equation 1f=(n2n1−1)(1R1−1R2)1f=(n2n1−1)(1R1−1R2)
The magnification m of an object m≡hiho=−didom≡hiho=−dido
Optical power P=1fP=1f
Optical power of thin, closely spaced lenses Ptotal=Plens1+Plens2+Plens3+⋯Ptotal=Plens1+Plens2+Plens3+⋯
Angular magnification M of a simple magnifier M=θimageθobjectM=θimageθobject
Angular magnification of an object a distance
L from the eye for a convex lens of focal length
f held a distance â„“ from the eye
M=(25cmL)(1+L−ℓf)M=(25cmL)(1+L−ℓf)
Range of angular magnification for a given
lens for a person with a near point of 25 cm
25cmf≤M≤1+25cmf25cmf≤M≤1+25cmf
Net magnification of compound microscope Mnet=mobjMeye=−diobj(feye+25cm)fobjfeyeMnet=mobjMeye=−diobj(feye+25cm)fobjfeye
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