Compute the focal length in air of a thin biconvex lens (n=1.5) having radii of 20 and 40 cm. Locate and describe the image of an object 40cm from the lens.(adsbygoogle = window.adsbygoogle || []).push({});

my answer:

1/f = (n-1)(1/R1-1/R2)

1/f = (1.5-1)(1/20-1/40)

1/f = .5(.025)

f = 1/.0125 = 80cm (convering lens because f is positive)

Mt=-f/x0=-80/40=-2cm (Inverted image because Mt is negative)

Did I use the correct equations?

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Optics question

**Physics Forums | Science Articles, Homework Help, Discussion**