How to calculate Image height?

Question

A converging lens has a focal length of 52.00 cm. A 14.0-cm-tall object is located 131.0 cm in front of this lens. (a) What is the image distance? (b) What is the image height? Be sure to include the proper algebraic sign.

Thank you

Answer 1

A converging lens has a focal length of 52.00 cm. A 14.0-cm-tall object is located 131.0 cm in front of this lens. (a) What is the image distance? (b) What is the image height? Be sure to include the proper algebraic sign.

See:

http://en.wikipedia.org/wiki/Lens_(optic...

Let:

o = object-distance

i = image-distance

f = focal-distance

then:

1/o + 1/i = 1/f

magnification = i / o

1/131 + 1/i = 1/52 eq 1/i = 1/52 - 1/131 eq 1/i = (131-52)/(52*131) eq

i = (52*131)/(131-52) [cm] (image is real and toward the back-side of the lens!)

magnification = 86/131

image height = 14.0 * (86/131) = 9.2 [cm]

Good luck.