Lensmaker power, magnification and image signs
A thin spherical lens in a common surrounding medium has 1/f=(n_lens/n_medium−1)(1/R₁−1/R₂).
Key knowledge
A thin spherical lens in a common surrounding medium has 1/f=(n_lens/n_medium−1)(1/R₁−1/R₂). Its transverse magnification is m_T=h_i/h_o=−d_i/d_o: a negative magnification reverses orientation, while d_i<0 denotes a virtual image in the adopted object/image convention.
Values and equations
1/f=(n_lens/n_medium−1)(1/R₁−1/R₂); m_T=h_i/h_o=−d_i/d_o
- f,R₁,R₂,d_i,d_o,h_i,h_o
- Focal length, radii, image/object distances and heights m
- n_lens,n_medium,m_T
- Indices and transverse magnification
Conditions and scope
- Paraxial geometric optics, lens thickness negligible and identical medium on both sides; R is positive when its curvature center is downstream along incident light and negative upstream.
- Reuses the thin-lens image equation; aberrations and finite aperture limit actual images. Real-object d_o>0, converging f>0 and real downstream d_i>0 in this convention.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
University Physics 3: 2-4-thin-lenses: Equations 2.14–2.22, first/second surface radius signs and thin-lens limit; excludes incorrect claim |m|>0 implies enlargement in example prose.
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Entry details
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- university-core.1
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- University core expansion