Electricity Simulations Analysis Worksheet for studying static electricity through balloon and sweater interactions.

Let’s go step by step through each question on the worksheet. We’ll use logic and simple counting to figure out what’s happening with the charges.

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Question 1: Count the number of positive and negative charges on each object in the simulation and determine the overall charge of each object.

We’re told:

- Sweater: +57, –57 → Overall = 0 (because 57 positives cancel 57 negatives)
- Balloon: +4, –4 → Overall = 0
- Wall: +54, –54 → Overall = 0

✔ So all objects start neutral — no net charge.

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Question 2: Click on the balloon and drag it over and rub the balloon against the sweater. What happens? Pull the balloon slightly away from the sweater and release it, does anything happen?

When you rub the balloon on the sweater, electrons (negative charges) move from the sweater to the balloon. That means:

- The balloon gains extra negative charges → becomes negatively charged.
- The sweater loses those negative charges → now has more positives than negatives → becomes positively charged.

When you pull the balloon away and release it, it will be attracted back to the sweater because opposite charges attract (negative balloon ↔ positive sweater).

So yes — something happens! The balloon moves back toward the sweater.

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Question 3: How drag the balloon over the sweater and rub it against the sweater. Describe what, if any thing, happens to the balloon/sweater.

Same as above — rubbing causes transfer of negative charges (electrons) from sweater to balloon.

Result:
- Balloon becomes negatively charged.
- Sweater becomes positively charged.
- They attract each other after being separated.

You might also see little “–” signs moving from sweater to balloon in the sim — that’s the electron transfer!

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Question 4: Count the number of positive and negative charges on each object in the simulation and determine the net charge... Compare to answer in #1.

After rubbing:

Assume 19 negative charges moved from sweater to balloon (this is typical in this sim — but let’s check based on common results):

Original counts:

- Sweater: +57, –57 → Net 0
- Balloon: +4, –4 → Net 0
- Wall: +54, –54 → Net 0

After rubbing (say 19 e⁻ transferred):

→ Sweater: Still +57 protons, but now only –(57 - 19) = –38 electrons
Net charge = +57 + (–38) = +19

→ Balloon: Still +4 protons, but now –(4 + 19) = –23 electrons
Net charge = +4 + (–23) = –19

→ Wall: Unchanged → +54, –54 → Net 0

Compare to #1: All were 0 before. Now sweater is +19, balloon is –19, wall still 0.

So total charge is conserved: +19 + (–19) + 0 = 0 → same as before!

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Question 5: Pull the balloon back toward the middle of the simulation and let it go. Describe what happens? How can you explain this occurrence?

Now the balloon is negatively charged, and the wall is still neutral (equal + and –).

But when a charged object comes near a neutral one, it can cause *polarization* — meaning the charges inside the wall shift slightly.

The negative balloon repels electrons in the wall, so the side of the wall closest to the balloon becomes slightly positive (since electrons move away), and the far side becomes slightly negative.

Even though the wall is still overall neutral, the nearby positive part attracts the negative balloon.

So — the balloon sticks to or is pulled toward the wall!

This is called induced charge separation or electrostatic induction.

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Final Answer:

1. Initial overall charges: Sweater = 0, Balloon = 0, Wall = 0
2. After rubbing: Balloon becomes negative, sweater becomes positive; balloon is attracted back to sweater when released.
3. Rubbing transfers negative charges from sweater to balloon → balloon negative, sweater positive → they attract.
4. After rubbing (assuming 19 e⁻ transferred):
- Sweater: +57, –38 → Net +19
- Balloon: +4, –23 → Net –19
- Wall: unchanged → Net 0
Total charge still 0 → conservation of charge holds.
5. When balloon is brought near wall, it induces polarization in wall → wall’s near side becomes positive → attracts negative balloon → balloon moves toward wall.