Terminology for Electrostatics The two basic principles behind static electricit

Question

Terminology for Electrostatics

The two basic principles behind static electricity that you experienced in the sticky-tape exploratory lab are

Like charges repel

Unlike charges attract

There are two types of charges, namely

negative charges: the smallest negative charge is on the electron

positive charges: the smallest positive charge is on the proton

The charge on the proton and the charge on the electron are the same in magnitude, but they have opposite signs. A neutral object has the same amount of positive charges as it has of negative charges.

Objects can acquire static charges through friction (rubbing the balloon against a sweater) or manual separation (in the sticky-tape portion of the lab). Either case results in an object that is no longer charge neutral, but has either lost some electrons and is therefore positively charged or gained some electrons and is therefore negatively charged.

When you take an electrostatically charged balloon and place it near a wall it will be attracted to the wall, although the wall is not charged. However, the molecules in the paint orient themselves in the following manner

The phenomenon where the object rearranges its charges but remains overall charge neutral is called charging by induction.

Conductors, Insulators, and More

When something bridges the distance between a charged object and a neutral object, there are two things that can happen as shown in the figure:

The insulator does not allow the negative charges to flow from the charged object to the initially uncharged object.
The conductor does allow the negative charges to flow from the charged object to the initially uncharged object.

Q12. Find out which materials are good insulators and describe two of these materials and their applications here.

Q13. Find out which materials are good conductors and describe two of these materials and their applications here.

Q14. Find out what the term semiconductor means and explain it. Find out which materials are semiconductors and describe two of these materials and their applications here.

Moving Charges

Moving charges are nothing else but electric currents.

Answer the Questions 9,10 11,12,13,14,16

Q9. There are several everyday life situations where we experience this electricity - now we can be more precise and say it is static electricity. Give two examples of everyday life experiences that you can think of and that were not covered here. Describe whether the charging is due to friction, charge separation, or charging by induction.

Q10. Do some research to find out how to show charging by induction using a comb, or another plastic item, and water.

Q11. Place a dry mixture of salt and pepper in a clear plastic bag. Take a plastic spoon or knife and rub it against a sweater or towel. Bring the plastic spoon or knife close to the plastic bag with salt and pepper. What do you observe? What is the explanation of what you observe?

Q12. Find out which materials are good insulators and describe two of these materials and their applications here.

Q13. Find out which materials are good conductors and describe two of these materials and their applications here.

Q14. Find out what the term semiconductor means and explain it. Find out which materials are semiconductors and describe two of these materials and their applications here.

Moving Charges

Q16. What are the units for the following electric quantities: voltage, current, and resistance.

Explanation / Answer

Ans 9

Example 1

When you are sitting on plastic chair for some time with wearing rubber sole shoes. Now when you leave the chair and touch any metallic or conducting object then you will get electric shock. This is due to charging by friction.

Example 2

When you rub plastic comb in your dried hair & then if you take this comb near to paper pieces, then it will attract paper pieces. It is due to charging by induction.

Ans 10

Charging of comb occurs when you rub the comb on your dry hair then electrons transfer takes place from one to another. Now when this comb you will bring near to paper pieces, it will attract paper pieces due to charge induced in paper.

Ans 11

When rubbing plastic knife with sweater then electrons will be transferred from sweater to knife. So knife is negatively charged due to friction. Now when you take this knife near to salt and pepper mixture then it will attract pepper because pepper is positively charged. Unlike charges attract each other.

Ans 12

One insulaor is Porcelain. It is used in separating two electricity transmission line.

Second is rubber, It is used in covering of various tools likscrew driver, pliar etc. which is used in electrical application.

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