Programming TI-83 for Snells

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Let's program your calculator to solve Snell's Law problems for refraction. ... Type in SNELLS (the keys automatically type in alpha mode) press ENTER.
Programming your Ti-83 calculator

Since you spent all that money on your fancy calculator (well your parents did anyway), why not learn to use more of its capabilities?

Let’s program your calculator to solve Snell’s Law problems for refraction.

Snell’s law is

n i sin θ i = n r sin θ r Usually we are given the two indices of refraction and the incident angle €

We want to solve for the refracted angle.

Turn on your TI-83 (or whatever model, they program pretty much the same • Press the PRGM key • Scroll over to NEW • Press ENTER • Type in SNELLS (the keys automatically type in alpha mode) press ENTER • press PRGM then scroll to I/O • scroll down to PROMPT (or press 2)ENTER

• Press ALPHA N • put in a comma • Press ALPHA θ (the 3 key) • The line should read Prompt N,€ θ • Press ENTER €

Don’t forget the comma

Now just type in the formula (for theta and N just press the APLHA key first) −1

sin ((sin θ ) / N)



Press 2nd QUIT Test your program • Try problem 37.15 from schaums • Press PGRM • Scroll down to SNELLS • press ENTER press ENTER again • It should prompt with • N= ? • type in 1.33 press ENTER • it will ask for the angle • type in 60,press ENTER (be sure your calculator is set to degrees) • You should get and answer of 41° after rounding

Let’s try a problem where light goes from water into air Light is incident from water (n = 1.33) into air. If the incident angle is 30°, at what angle does the light refract into the air?

Bring the program up • when it prompts for “N” just type in 1/1.33 (this is sometimes called the “relative index of refraction) • Type in the angle (30) Hit Enter • the refracted angle will be 41.7°

Isn’t this cheating? Not in my class. learning to program is a handy skill you can use in the future. (and calculators don’t make stupid mistakes after they stayed up until 3 in the morning writing a paper for English class)

Just make sure that you can always show your work and put units on your answers.