Focal Length and Radius

f = \frac{R}{2}

The focal length of a spherical mirror is half its radius of curvature.

Variables

Focal length

Radius of curvature

Your notes

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Other optics formulas with the same quantities

Spherical Mirror Focal Length (Reflection) shares Focal length, Radius of curvature
Thin Lens Equation (Lenses) shares Focal length
Lensmaker's Equation (Lenses) shares Focal length
Lens Power (Lenses) shares Focal length
F-Number (f-stop) (Optical Instruments) shares Focal length
Depth of Field (Optical Instruments) shares Focal length

Where this formula is listed

Optics formulas, under Reflection, alongside Law of Reflection, Mirror Magnification and Fresnel Reflection (Normal Incidence).
In the optics list it comes after Mirror Magnification and before Fresnel Reflection (Normal Incidence).
Optics formula sheet, one of 34 formulas printed with symbol keys and SI units.
The full formula index, grouped by category and topic.

Common questions

What is the Focal Length and Radius formula?

Focal Length and Radius is written f = R/2. The focal length of a spherical mirror is half its radius of curvature. It belongs to Optics, under Reflection.

What are the units in f = R/2?

In SI units, f is focal length, measured in m; R is radius of curvature, measured in m.