Lab 8: Electric Charge and Force

We started the day with a ballon experiment. Rubbing the ballon with hair will make the ballon to stay on the glass surface because when the ballon is rubbed it becomes a charged object, and when it stays on the surface of the glass, we know that both the balloon and the glass have opposite charges that attract each other.

 Here is our prediction of both cases. However, we could not see the second case to work effectively due to the climate. The second case consisted on rubbing the balloon with silk, it supposes to also stay on the glass surface.

 We conducted an experiment about interactions between scotch tape strips. First with two strips pasted on the table, we were to supposed to peel them off and cause and interaction with each other and see what the final result will be.

This video shows that both scotch strips repel each other, the reason is because both have the same charges when pulled off the table.

This is an example of just 1 scotch strip pasted on the table making interaction with a new scotch strip, and as we can see both attract each other due to the difference in charges.

 Then we placed two strips of tape on the table sticky side down and labelled them as B, also we placed another two strips on top of them.

 The results were that, T and T repelled each other, B and B repelled each other also, but T and B attracted each other.

 We worked on this problem example after watching a video of two magnetic balls. When a magnetic ball gets closer to the hanging ball, it moves apart. So we find the angle as a function of the length of the rope and the distance is moved, which is θ = arcsin(X2/L). Then we found the force acting on the ball. F = mg(tanθ). Then we substituted θ in order to get  F = mg(tan(arcsin(X2/L)), which will be needed for the next experiment.

 We started working on the Coulomb electric force law video. This is our data and graph after doing what was asked in the lab manual. We fit our curve with an inverse function of degree two.

 We work on an example using Coulomb's Law.

 We decomposed the force into x and y components.

We conducted an experiment using the Van De Graff generator. When is turned on, the paper streamers start to float on the air because they have the same charge. Here we put a pie pan on top of it, when we turned the machine on, it flew away.

In this video we can see that if you put your hand on the Van De Graff generator, you will get electric charges. Also, when the hand was taken away, the paper strips started to float.

We put a Franklin motor on it.

 The charges generated by the device are spread out until it reaches the top of the Franklin motor, causing it to rotate. The strips don't float anymore because all the charges go to the motor.

Finally, we used Coulomb's law and the Universal Gravitation law in order to find the ratio of forces between them. Our result was 4.182x10^42.

Conclusion

Here are the answers to the conclusion section.