top of page
Convex Lenses: Focal Length and Optics Science Experiment

How can you find the focal length of a lens? Does the type of lens matter? This is a super simple procedure measure a lens' focal length. Comparing lenses of different focal lengths is easy using this activity. 


Questions Answered:

  • How do you find the focal length of a lens? 
  • How does the image from a lens with a long focal length compare to one with a short focal length?


Topics Addressed:

  • Convex lenses make real images. 
  • The focal length of lenses can be measured using their ability to make images. 
  • Lenses with long focal lengths make larger, dimmer images than those with shorter focal lengths.


Learn to use scientific equipment:

Converging (convex) lenses


Skills and Tasks involved:

Find the focal length of convergent lenses. 


Materials Needed

convex lens, concave lens, convex mirror, concave mirror


Preparation Time

none needed


NOTE: This activity is part of the Light, Optics, & Color Unit found here.

Convex Lenses: Focal Length and Optics Science Experiment


    Answer Keys and Teacher Notes address most questions and issues that might arise in this study—you shouldn’t have to do any outside research unless you want to.

    Connect with me: If you have questions or problems, please let me know and I’ll get back to you as soon as I can.


    This resource (along with all resources sold on this site) can be found inside the membership. For information on that option, click here.

    Terms of Use   Copyright © Carolyn Balch. All rights reserved by the author. This product is to be used by the original downloader only. Copying for more than one teacher, classroom, department, school, or school system is prohibited. This product may not be distributed or displayed digitally for public view. Failure to comply is a copyright infringement and a violation of the Digital Millennium Copyright Act (DMCA). Clipart and elements found in this PDF are copyrighted and cannot be extracted and used outside of this file without permission or license. Intended for classroom and personal use ONLY.

    Related Products