**Practice Problems**

**Practice overview**

These practice problems are not graded. You will receive automatic feedback written by your instructors for each of the problems. Feel free to use the reference sheets provided.

Your instructors will not actually get your scores on these problems, so please e-mail them with any questions you may have.

Practice Question #1

This problem requires you to solve for the focal length given several variables.

Practice Question #2

This problem also requires you to solve for the focal length given several variables, with a twist.

**Formative evaluation - practice
problems **

Formative evaluation #3: This is a quick survey on your impression of the lesson practice questions.

Note: you only have to enter your real name at the top of the survey. There is no ID number, and the e-mail address is optional.If you had issues with these two problems, review the materials again. Take the posttest when you feel you are ready, by your instructor's deadline.