Question

Experiment 2: Static Materials
In this experiment, you will investigate the phenomenon of static electricity of various materials.

Materials
Electrostatics Kit Materials
*Paper (Any Kind)
*Flat Work Surface     

  
Procedure
1.   Tear the paper into small pieces (approximately the size of a hole-punch) and scatter them in a small area on a table or flat surface.
2.   Choose one plastic strip (acetate [light blue and transparent], vinyl [no color and transparent], or polyethylene [white and translucent]) and one fabric (wool or cotton cloth) from the electrostatics kit.
3.   Quickly rub the fabric up and down the length of the plastic strip for approximately 20 seconds.
4.   Bring the plastic strip near the small, torn pieces of paper.
5.   Record observations about the amount picked up and behavior of the paper in Table 2.
6.   Repeat Steps 2 – 5 for five additional fabric and plastic combinations.

Table 2: Static Electricity Properties of Various Materials

Type of Plastic	Type of Fabric	Observations

  
    Post-Lab Questions

1.   What happens when you bring the charged plastic strip near the paper pieces? Why does this happen?

2.   Draw a free body diagram of the forces acting on the piece of paper.

3.   Why does the electric force easily overcome the force of gravity and lift the paper off the surface without even touching the paper?

4.   Which of the materials pick up positive charge and which pick up negative charge? How did you determine this?

Answer 1

Concept required- The question requires the concept of Induction charging process. In this process, the material is charged by bringing another charged particles near the uncharged object without touching the two objects

Solution-

Part 1- When we bring the charged plastic strip near the paper pieces , paper pieces are attracted towards the chargged plastic strip. This process happens due to the process of induction. When We rub the plastic strip with the fabric, we provide energy to the electrons in the plastic strip. Thus after they get energized, they are knocked off the strip, and hence the strip becomes positively charged due to the deficiency of the electrons

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Part 2 -

The free body diagram of a paper strip is as follows -

The electrostatic force will act in upward direction , while the gravitational force will act downwards ( no wonder there ;) )

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Part 3 -

The gravitational force is very very less compared to the electrostatic force exerted by the charged plastic strip without even touching the paper.

(m = mass, g =acceleration due to gravity)

(Q = charge on the strip , r = distance between the strip and the paper bits)

As we can see the mass of the paper strip is very very less, while the charge on the strip is higher, moreover if the distance between them is also lesser, then the electrostatic force easily overcomes the gravitational force, and hence lifts off the paper easily

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Part 4 -

Positive charge is acquired by loosing the electrons, and negative charge is acquired by excessive electrons.Now the Electrons are knocked off a material in a way we discussed above in Part 1, while the electrons are gained by absorbing the electrons lost by another material. Usually this process is complementary, the substance we rub is positively charged , while the substance upon which it is rubbed is negatively charged.

So if we rub the fabric up and down the plastic strip, we are making the plastic strip positively charged, and the fabric negatively charged.

And that's How we get the answer :0

Please note that the Observation table is yours to fill to gain extensive knowledge of this part :0