Lens and mirror calculator
Pick a lens or mirror, give its focal length and the object distance, and get where the image forms, its magnification and nature - with the New Cartesian sign convention, the working and the ray diagram.
Answer
- Image distance v
- -10 cm
- Magnification m
- 0.3333
- Image is
- diminished, erect, virtual
Ray diagram
Working
- Sign convention: distances are measured from the lens, positive in the direction the light travels; so u = -30 cm and f = -15 cm.
- 1/v - 1/u = 1/f: 1/v = 1/f + 1/u = 1/(-15) + 1/(-30), so v = -10 cm.
- m = v/u = 0.3333; image height = m × object height = 0.3333 cm.
Power of the lens P = 100/f(cm) = -6.667 D.
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