Exam Krackers 1001 Physics #950

[TopTomato]

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EDIT not number 950 but 949

The magnification of a 3 cm object is placed 5 cm from a certain lens is -1. Where is the image formed?

Ok so from the equation M = -di/do I get di=5 cm. And since M is negative the image is a real inverted imagine, so how can the answer be 5 cm behind the lens? My answer was 5 cm IN FRONT of the lens.

 

[jtran7]

if di is positive it is a real image

real images are points where the light rays end up so for a lens the light rays are refracted not reflected therefore a positive di is behind the lens

if it was a mirror positive di would be in front

 

[TopTomato]

if di is positive it is a real image

real images are points where the light rays end up so for a lens the light rays are refracted not reflected therefore a positive di is behind the lens

if it was a mirror positive di would be in front

Ahhhhh ok thanks man! Getting confused between the mirrors and lenses

 

[jtran7]

no problem!