Explain:
“One of the first indications that atoms are not indivisible, comes from studying static electricity and the condition under which electricity is conducted by different substances.”
Question from: NCERT Science for Class 9.
Chapter: Structure of an Atom
Answers
Answer:
This lesson is the first of a four-part series on static electricity. These lessons are meant to help students understand that static electricity is a phenomenon that involves positive and negative charges.
An understanding of static electricity must begin with the concept that all matter is composed of atoms, and all atoms are composed of subatomic particles among which are the charged particles known as electrons and protons. Protons carry a positive charge (+), and electrons carry a negative charge (-). The number of electrons in an atom—ranging from one up to about 100—matches the number of charged particles, or protons, in the nucleus, and determines how the atom will link to other atoms to form molecules. Electrically neutral particles (neutrons) in the nucleus add to its mass but do not affect the number of electrons and so have almost no effect on the atom's links to other atoms (its chemical behavior).
To further understanding about static electricity, you should help your students to make connections between their day-to-day experiences with static electricity—such as lightning, receiving shocks after shuffling across a carpet, taking clothes that cling to each other out of the dryer, combing their hair in the wintertime—with the static activities conducted in the classroom. Ask them to try to describe and explain their everyday experiences with static in the terms they are learning: repel, attract, static charge, electron transfer. It is important that students grasp the concept that oppositely charged objects attract each other and like charged objects repel each other. It is less important that they are able to recall which materials tend to acquire negative or positive charges.
When two different materials come into close contact, for example, felt rubbing against a balloon or two air masses in a storm cloud, electrons may be transferred from one material to the other. When this happens, one material ends up with an excess of electrons and becomes negatively charged, while the other ends up with a deficiency of electrons and becomes positively charged. This accumulation of imbalanced charges on objects results in the phenomena we commonly refer to as static electricity.
When students first begin to understand atoms, they cannot confidently make the distinction between atoms and molecules. Students often get the idea that atoms somehow just fill matter up rather than the correct idea that the atoms are the matter. Middle-school students also have trouble with the idea that atoms are in continual motion. Coming to terms with these concepts is necessary for students to make sense of atomic theory and its explanatory power. (Benchmarks for Science Literacy, p. 75.)
In Static Electricity 1: Introducing Atoms, students are asked to review websites to learn about the atom's basic structure and the positive and negative charges of its subparticles. This lesson lays the groundwork for further study of static and current electricity by focusing on the idea of positive and negative charges at the atomic level. Due to the amount and complexity of the information related to this topic, students will gain an understanding of these concepts over time. It is important that they explore this topic in a variety of contexts.
Static Electricity 2: Introducing Static Electricity helps expand students' concepts about atoms and how they relate to static electricity. In this lesson, students perform some simple experiments, creating static electricity to demonstrate how opposite charges attract each other and like charges repel each other. Then, students explore a website that further explains these concepts.
Static Electricity 3: More About Static Electricity helps expand students' concepts about atoms and how they relate to static electricity. In this lesson, students explore a website to investigate concepts related to static electricity. Then, students perform experiments in which they create static electricity and demonstrate how opposite charges attract each other and like charges repel each other.
Static Electricity 4: Static Electricity and Lightning introduces students to concepts about lightning and how they relate to static electricity. In this lesson, students explore a variety of websites to learn about lightning and then explain in their own words what causes lightning and how it is related to static electricity.
Answer:
THIS NEEDS THE CONCEPT OF STATIC
Explanation:
STATIC ELECTRICITY:
Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it is able to move away by means of an electric current or electrical discharge.
KNOW MORE:
Static electricity is the imbalance of electric charge on a surface of a material. Static means fixed or stationary, therefore it is used in contrast to dynamic (moving) electricity which are in the form of electric currents.
Typically atoms are neutral, which means they have the same number of electrons and protons. However atoms become charged when there is an imbalance in the amounts of these particles, which can happen fairly easily for certain materials. The ability for a material to hold on to its electrons determines its place in the "triboelectric series".[2] The farther two materials are ranked in this series, the more noticeable the charge separation is when they come in contact. For example glass and silk are relatively far apart in this series, so when glass is rubbed with silk it will lose many electrons to the silk, and static electricity can be observed.[2]
Charging
Figure 2. Charge-induced separation.[3]
Charge separation of two objects can be induced in several different ways.
Contact-induced separation is accomplished by rubbing two objects together, since objects in contact form a chemical bond known as adhesion. Adhesion is the tendency for different surfaces to cling to one another. Friction is often assumed to be the cause of this static charging, but friction is actually caused by adhesion and shockingly has no influence on charge separation.[4]
Heat and Pressure-induced separation occurs when certain types of crystals or ceramics have a stress applied to them, or are heated.
Charge-induced separation occurs when a charged object is brought close to a neutral one. The charges inside of the neutral object of the same polarity as the charged object will be repelled while charges of the opposite polarity will be attracted to it. This causes the once neutral object to have an imbalance of charge. This can be seen in Figure 2.
Discharging
Figure 3. Lightning is the discharge of static build-up in thunder clouds.[5]
Once an object has built up a charge imbalance, it will naturally want to become neutral once again. This happens by what is called discharging, which can commonly be felt by a shock when it happens to a person. Contact-induced charging is the most commonly experienced form of static electricity build up, as can be accomplished by rubbing ones feet on the carpet. Once enough charge is built up, there is a high enough voltage needed to cause the charge to jump from the person to a nearby doorknob leaving the person discharged and, if they weren't ready for it, quite shocked.
This same charge build-up and discharge process occurs in clouds to create lightning, and can be explored on Hyperphysics.