# Homework Help: Imagine that you are conducting an activity with a laser...

1. Feb 10, 2017

### AlexisFair

1. The problem statement, all variables and given/known data
Imagine that you are conducting an activity with laser to create an interference pattern. Use the appropriate equations to predict two ways to change the interference pattern in order to have closer fringes. Explain your predictions.

Change in X = L(Lambda) / d

2. Relevant equations

3. The attempt at a solution
Prediction One

The formula provided, shows that the distance between the fringes ( X) is proportional to the distance from the slits to the screen (L). Meaning, increasing one will increase the other. As a result, decreasing the distance from the slits to the screen (L) will decrease the distance between the fringes.

Prediction Two

The formula provided, shows that the distance between the fringes (X ) is inversely proportional to the distance between the two sources (d). Meaning, increasing one will decrease the other. As a result, Increasing the distance between the two sources , or slits (d) will decrease the distance between the fringes.

It says I need two predictions, but I think I found a third possibility, which is "Decreasing Lambda since it's proportional to X, just like L."

Because of this "Third possibility" I'm doubting my answers that I provided. I was wondering if this forum could look over my results to see if I missed something or if my answer is incorrect.

I'm new to the forum and I hope this forum will help and guide me through grade 12 physics. Thank you .

2. Feb 10, 2017

### BvU

Hello Alexis,

Good reasoning. Since there are three factors that play a role, you can expect three ways to influence the result, so no worries needed.

One small opportunity for improvement: the sentence
can easily be misunderstood. It might be safer to say something like "If $\Delta X$ is the distance between fringes, then $\Delta X \propto \lambda L/d$.

I think the exercise composer asks for two because varying the distance Ln to the screen is rather trivial ...

3. Feb 10, 2017

### AlexisFair

Yeah, my sentences are quite repetitive but I did not want to fix it up, yet, as I wanted to ensure my answer was correct. So just to make sure, should I change anything? (Other than improving the sentence structure.) Or should I add in that third possibility?