Spherical Mirror Equation Calculator
Find image distance and magnification using 1/f = 1/u + 1/v
Parameters
Controls
Calculated Values
Examples
u=25, f=12
Concave mirror.
Visualization
Spherical Mirror Equation
Geometric optics treats light as rays obeying reflection and refraction laws. For thin lenses and spherical mirrors, the Gaussian lens/mirror equation 1/f = 1/u + 1/v relates object distance u, image distance v, and focal length f (all measured from the optical element, with sign conventions).
Magnification m = −v/u compares image height to object height; negative m means inverted image. Real images form where light actually converges (v > 0 for lenses in standard convention); virtual images appear behind the element (v < 0).
Concave mirrors (f > 0) form real inverted images for objects beyond C; convex mirrors always give virtual upright diminished images.
Ray tracing uses three principal rays: parallel to axis → through focus; through center → undeviated; through focus → emerges parallel. Combined with the equation, this predicts image position, size, and orientation for cameras, eyes, microscopes, and projectors.
Class 12 NCERT Ray Optics covers lenses, mirrors, power in diopters P = 1/f (f in meters), and combination of thin lenses in contact: P_total = P₁ + P₂.
Key Concepts
- 1/f = 1/u + 1/v
- m = −v/u
- P = 1/f (diopters)
- f = R/2 for mirrors
- Real vs virtual image
- Principal ray construction
Real-World Applications
- Cameras and smartphone lenses
- Eyeglasses and contact lenses
- Microscopes and telescopes
- Concave/convex mirrors in vehicles
- Class 12 ray optics problems
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Find image distance and magnification using 1/f = 1/u + 1/v.
- Lens Power
Convert focal length to diopters and combine thin lens powers.
- Critical Angle
Find critical angle for total internal reflection between two media.
- Diffraction Grating
Calculate diffraction angles using d sin θ = mλ.
Physics Equations
Step-by-Step Solution
See how the main results are calculated.
Step 1: Mirror Equation
Equation:
Explanation:
Same form as lens; f = R/2 for spherical mirrors.
Step 2: Values
Result:
Step 3: Image Distance
Calculation:
Result:
Step 4: Magnification
Equation:
Result:
Step 5: Real vs Virtual
Real image (screen)
Explanation:
Concave mirror: object beyond C gives real inverted image.
Step 6: Focal Length
Equation:
Explanation:
Radius of curvature R = 2f.
Frequently Asked Questions (FAQ)
Convex vs concave?
Concave converges; convex diverges.
Why same equation as lens?
Paraxial reflection law gives identical Gaussian form.
Practice MCQs
- Concave mirror f is:
- f = R/2 means R = 24 cm gives f =
- Convex mirror image is always:
- Same as lens equation:
- Object at focus of concave mirror:
- Magnification |m| < 1 for convex mirror means:
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