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Ray Optics — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsRay Optics1 Mark
Question

An object is placed first at infinity and then at 20 cm from the object side focal plane of the convex lens. The two images thus formed are 5 cm apart. The focal length of the lens is

(a) 5 cm  

(b) 10 cm

(c) 15 cm

(d) 20 cm
✓

Answer

(b) 10 cm

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