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A magnified, inverted image is located at a distance of 40.0 cm from a bi-convex lens with a focal length of 12.0 cm. The object distance is
17.2 cm
15.9 cm
10.5 cm
9.23 cm
7.05 cm

Respuesta :

tiara143
The object distance is 17.2 cm

As we know, the lens formula is [tex] \frac{1}{f} [/tex] = [tex] \frac{1}{v} [/tex] + [tex] \frac{1}{u} [/tex] 

where v = image distance from the lens
u = object distance from the lens
f = focal length of the lens 
Alos, focal length of convex lens is positive.

⇒ [tex] \frac{1}{12} [/tex] = [tex] \frac{1}{40} [/tex] +[tex] \frac{1}{u} [/tex]

⇒ [tex] \frac{1}{u} [/tex] = [tex] \frac{1}{12} [/tex] - [tex] \frac{1}{40} [/tex]

⇒ [tex] \frac{1}{u} [/tex] = [tex] \frac{10-3}{120} [/tex]

⇒[tex] \frac{1}{u} [/tex] = [tex] \frac{7}{120} [/tex]

⇒ u = [tex] \frac{120}{7} [/tex] = 17.2 cm

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