Drag the object • Adjust focal length • Watch ray tracing in real time
Focal Length f
f = 15 cm
Object Distance |u|
u = −30 cm
Object Height h
h = 3 cm
Drag the arrow to move the object
Object distance u
—
Image distance v
—
Magnification m
—
Image nature
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📋 CBSE Practical: u–v Table
No readings yet. Move the object and click "Record Reading".
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u (cm)
v (cm)
f calc = uv/(u+v)
m = −v/u
Nature
📈 u–v Graph (intersection of tangent with axes ≈ 2f)
Sign Convention (New Cartesian): All distances measured from the pole/optical centre.
Distances in the direction of incident light are positive;
against incident light are negative.
For mirrors: u is always −ve (object in front). v is −ve for real image, +ve for virtual.
For lenses: u is always −ve. v is +ve for real image, −ve for virtual.
Focal length: concave mirror & convex lens = negative f (mirror) / positive f (lens).