Why Was My Answer of 63 cm for the Focal Length of a Converging Lens Incorrect?

Thread starter syllll_213
Start date Apr 15, 2025

Click For Summary

The focal length of a converging lens is determined using the lens formula, which relates object distance, image distance, and focal length. In this case, the object distance is 14 cm and the virtual image is located 18 cm from the object, resulting in an image distance of -4 cm (since virtual images have negative distances). Applying the lens formula (1/f = 1/do + 1/di) reveals that the correct focal length is not 63 cm. The error likely stems from miscalculating the image distance or not properly applying the lens formula. Understanding these calculations is essential for accurately determining the focal length of a lens.

Apr 15, 2025

syllll_213

Homework Statement: An object is in a distance of 14 cm from a converging lens. The lens produces a virtual image at a distance 18 cm from the object.

What is the focal length of the lens (in cm).

Relevant Equations: 1/f = 1/di + 1/do

I attempted and keyed in the answer as 63 but I was graded wrong. What am I missing?

Physics news on Phys.org

Apr 15, 2025

haruspex

Science Advisor

Homework Helper

Insights Author

Gold Member

2024 Award

syllll_213 said:

Homework Statement: An object is in a distance of 14 cm from a converging lens. The lens produces a virtual image at a distance 18 cm from the object.

Thread 'Bernoulli vs real life experiment'

If have close pipe system with water inside pressurized at P1= 200 000Pa absolute, density 1000kg/m3, wider pipe diameter=2cm, contraction pipe diameter=1.49cm, that is contraction area ratio A1/A2=1.8 a) If water is stationary(pump OFF) and if I drill a hole anywhere at pipe, water will leak out, because pressure(200kPa) inside is higher than atmospheric pressure (101 325Pa). b)If I turn on pump and water start flowing with with v1=10m/s in A1 wider section, from Bernoulli equation I...

View full post »