Activity: Charging by Friction and Laws of Electrostatics

Activity: Charging By Friction and Laws of Electrostatics

In this activity, you will explore a few concepts of electrostatics: charging by friction, the law of attraction and repulsion, and the triboelectric(or electrostatic) series.

NOTE: During this activity, you may need to remove the charge on a charged object. This can be done by simply wiping the object with your hands. You can verify that the charge has been removed by bringing the object close to a neutral strip on the watch glass. There should be no attraction or repulsion.

Part A: Exploring charges

1. Rub one end of a green plastic strip with a piece of fur and balance the strip on a watch

glass. Be careful not touch the end you just rubbed. The watch glass should be able to spin freely

without the strip hitting the table top.

2. Rub an ebonite rod with a piece of fur. The ebonite will now have a negative charge.

(Ebonite rubbed with fur is a standard charged object. Memorize its charge.)

3. Bring the ebonite rod close to the green plastic strip.

What did you observe? ______

What must be the charge on the green plastic strip? ______

4. Rub one end of another green strip with fur and bring it close to the green strip on the watch

glass.

What did you observe? ______

substances rubbed / charge on
object A / substance which lost electrons / substance which gained electrons
object A / object B
ebonite / fur
green plastic / fur

Base on your observations:

1. Which is higher in the triboelectric series: green plastic or fur?

2. Which is higher in the triboelectric series: ebonite or fur?

3. How could you determine whether ebonite is higher or lower than green plastic in the

triboelectricseries?

Part B: Developing aTriboelectric Series

1. Rub one end of a green plastic strip with a piece of fur and balance the strip on a watch

glass. The watch glass should be able to spin freely without the strip hitting the table top.

2. Determine the charge on the green strip using an ebonite rod and fur.

**The charge on the green strip is ______

You will be comparing other charged objects to the green strip on the watch glass.

Remember its charge.

3. Rub one end of another green strip with one end of an acetate strip. Bring the charged end of the

green strip close to the green plastic strip balanced on the watch glass.

What did you observe? ______

What is the charge on the green strip? ______

4. Bring the charged end of the acetate strip close to the green plastic strip on the watch glass.

What did you observe? ______

What is the charge on the acetate strip? ______

5. Repeat steps 2-4 with i) the ebonite and acetate strip and ii) the ebonite and the green strip.

substances rubbed / attracted or repelled the green strip on watch glass / negatively or positively charged / lost or gained electrons
1. / green plastic
acetate
2. / ebonite
acetate
3. / ebonite
green plastic
weaker hold on electrons (+)

stronger hold on electrons (-) / Substance

6. Using the data you collected, determine the

correct order of ebonite, green plastic, and

acetate in the triboelectric series.

Lab QUIZ: Charging By Friction and Laws of Electrostatics Name ______

[5] 1. a) Copy your results from the lab activity into the table below.

[2] b) Explain your reasoning for determining whether acetate or ebonite is higher in the triboelectric series.

______

[3] c) In order to place fur into the triboelectric series above , ebonite and green plastic were rubbed with

the fur. The ebonite and green plastic both obtain a negative charge when rubbed with fur and repel a

negatively charged strip on a watch glass. To determine the position of fur in the triboelectric series,

weaker hold on electrons (+)

stronger hold on electrons (-) / Substance

i) rub the fur with the ______

weaker hold on electrons (+)

stronger hold on electrons (-) / Substance

[2] 2. What are the two laws of electrostatics:

ii)

[2] 3. Three objects made of different material were tested to determine their order in the triboelectric series.

All three objects were tested with a positively charged acetate rod. The results are shown in the table

below.

substances rubbed / attracted or repelled the acetate rod
1. / object A / attracted
object B / repelled
2. / object A / attracted
object C / repelled
3. / object B / attracted
object C / repelled

a) Place the three objects in the triboelectric series below.

weaker hold on electrons (+)

stronger hold on electrons (-) / Substance

[3] b)Object A and Object B are rubbed together. Show the charges in each substance.

i) before rubbing ii) rubbing iii) after rubbing

Object A Object B Object B Object A Object B

Object A

triboelectric series

+ acetate strip (*glass rod and acetate seem interchangeable depending on strip on watch glass)

glass rod

fur

ebonite rod

acrylic

– green plastic strip

*when green strip (- ve) (charged with fur) is placed on watch glass, acetate (-ve) and glass (+ve)

But when acetate strip (+ve) (charged with fur) is placed on watch glass, acetate (+ve) and glass (-ve)