Question

Two converging lenses with focal lengths of 40 cm and 20 cm are 14 cm apart. A 4.0 cm -tall object is 14 cm in front of the 40 cm -focal-length lens. Calculate the image position. Answer must be in cm (ps it is not 45.8 or 35.5)

x=________cm from the object

Answer 1

Answer 2

Start with the first lens 1/40 1/14+1q -22.22 cm (meaning its 22.22 cm in from of that lens. Since the lenses are 14 cm apart, that image is 36.22 cm from the second lens, and we will use that as the object distance for the second lens 1/20 1B6.221/q 43.47 cm This means the final image is 43.47 cm in back of the second lens The distance between the object and the image is adding the distance from the object to the first lens+ the lens separation + the distance the final image is away from the second lens. D- (14+14 +43.47) 71.4 cm