E-CodeThin lens, mirror, lensmaker and two-lens system — a TI-84 Plus CE program
LENS is a TI-BASIC program for the TI-84 Plus CE. Thin lens or mirror (1/f = 1/do + 1/di; real is positive — f > 0 for a converging lens or concave mirror, di < 0 means virtual, negative magnification means inverted): image distance, magnification, image height and real/virtual, upright/inverted; the lensmaker's equation for a lens in air with power in diopters (R > 0 for a surface convex toward the object: biconvex R1 > 0, R2 < 0); and a two-lens system with total magnification and equivalent focal length.
What it asks for and what it shows
It asks for 3 values at its prompts, after you pick option 1 from its menu. In the example below it shows DI CM, MAG, HI CM, REAL, INVERTED, REDUCED.
Example run
One of its oracle test cases: “converging lens, object beyond 2F”. The inputs are typed in order, and the results are the values the case expects on the screen.
| Step | Value |
|---|---|
| You enter | |
| Menu | option 1 |
| Input 1 | 10 |
| Input 2 | 30 |
| Input 3 | 2 |
| The screen shows | |
DI CM= | 15 |
MAG= | -0.5 |
HI CM= | -1 |
| Text | REAL |
| Text | INVERTED |
| Text | REDUCED |
How it's checked
8 test cases, each checked against an independent method. Replayed key by key on a virtual TI-84 Plus CE, they make 51 checks.
How E-Code checks every program
Run it or put it on your calculator
- Open the library in the TI-84 Plus CE calculator and pick “Thin lens, mirror, lensmaker and two-lens system” (LENS).
- Put it on your own calculator with a computer and a USB cable, or type it in by hand.
Related programs
- Refraction: Snell's law and total internal reflection
- Projectile motion solver
- Kinematics: the five constant-acceleration equations
- Projectile launched from a height
- Simple harmonic motion: spring or pendulum
All TI-84 Plus CE physics programs · All TI-84 Plus CE programs