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ELECTROSTATIC POTENTIAL

An object at a certain height from the ground will always have some energy called potential energy. Similar to that a charge at a  certain distance from another charge will also have an electrostatic potential.

The electrostatic potential V at any point is defined as the work done in bringing a unit positive charge from infinity to that point.

In bringing the unit positive charge from infinity to a point, we must do some work against the force of repulsion (if we assume that  another charge is also positive)

The Work done by the force in bringing a unit positive charge from infinity to a point will be equal to the electrostatic potential (V ) at that point.

Potential due to a point charge, q  is given by       V = q / 4πε0 r

where q - charge, ε0 - permittivity of free space  and r - distance between the charges

EQUIPOTENTIAL SURFACES

An equipotential surface can be defined as the surface which will have a constant value of the potential at all points on its surface.

We get the energy to do all our work in our daily life from different sources.  Do you know what the source of energy for the plant life and animal life on our planet is? Yes, you are right!  It is the sun which gives out light and heat for all the lifeforms on EARTH. But from where the   SUN  gets its energy?  It is obtained from the atoms present in the sun mainly from HELIUM  and HYDROGEN. The nuclear reactions of the atoms of these two elements continuously produce the necessary energy for the sun to survive for millions of years in the Milky Way Galaxy.  These reactions are called  NUCLEAR FUSION.

In nuclear fusion, two NUCLEI  of HYDROGEN  fuse together to form a HYDROGEN nucleus. A large amount of heat and light energy will be emitted, and that is being radiated into space, in this process.  Our planet earth  receives that  energy  and all the life forms survive.

Before we understand the process of nuclear fusion reactions that take place in the sun and distant stars, let us understand the process of a nuclear reaction that takes place in our planet, that is  NUCLEAR FISSION.   

Fission
After the discovery of the neutron. Enrico Fermi found that when neutrons bombard various elements, new radioactive elements are produced. However, when a neutron was bombarded on a uranium target, the uranium nucleus broke into two nearly equal fragments releasing a great amount of energy. An example of such a reaction is

n + U 235  ---> U 236 ---> Ba 144  +  Kr89 + 3n
Fission does not always produce barium and krypton. A different
pair can be produced, for example,
 n  +  U235  ---> U236 --->Sb133 + Nb 99 + 4 n

Still another example is
 n + U235 --->  Xe 140   +  Sr94 +   2 n
The fragment nuclei produced in fission are highly neutron-rich and unstable. They are radioactive and emit beta particles in succession until each reaches a stable end product.
The energy released (the Q value ) in the fission reaction of nuclei like uranium is of the order of 200 MeV per fissioning nucleus.

Energy can be released if two light nuclei combine to form a single larger nucleus, a process called nuclear fusion. Some examples of such energy liberating  reactions are

1H +  1H ---> 1H 2  + e+ v + 0.42 MeV
1H + 1H  ---> 2He + n + 3.27 MeV

To generate a useful amount of energy, nuclear fusion must occur in bulk matter. What is needed is to raise the temperature of the material until the particles have enough energy – due to their thermal motions
alone – to penetrate the Coulomb barrier. This process is called thermonuclear fusion.

Thus, for thermonuclear fusion to take place, extreme conditions of temperature and pressure are required, which are available only in the interiors of stars including the sun. The energy generation in stars takes place via thermonuclear fusion.

In the sun the fusion reaction is a multi-step process in which hydrogen is burned into helium; hydrogen is the ‘fuel’ and helium the ‘ashes’. This is called a proton-proton (p, p) cycle.

The first thermonuclear reaction on earth occurred at Eniwetok Atoll on November 1, 1952, when USA exploded a fusion device, generating energy equivalent to 10 million tons of TNT (one ton of TNT on explosion releases 2.6 × 1022 MeV of energy).
A sustained and controllable source of fusion power is considerably more difficult to achieve. It is being pursued vigorously in many countries around the world (including India) because fusion reactor is regarded as the future power source.

A lesson plan is the instructor’s road map of what students need to learn and how it will be done effectively during the class time. 5 step learning method provides Experiential learning, Higher order thinking skills for students to learn vital academic concepts. These academic concepts are presented in a number of activity based learning opportunities for the students that are crafted to foster critical thinking, reasoning, and active engagement with the topics. These lessons based on the 5-Step method ensure that teachers have the best possible delivery method while also giving them a strong experiential foundation in which they can infuse their own creativity and experience to personalize the lessons.

Aim      Action     Analysis     Application      Assessment

Aim is the clear learning objective. Both the teachers and students have a clear understanding of the learning goals (Aim) of the lesson. This step helps develops conscientiousness in students.

Action is the 2^nd A of teaching where teacher uses resources and materials for teaching. Sometimes teacher also make use of role playing, Drama, Demonstration, story telling, Experimentation in the classroom.

Analysis is the 3^rd step where the teacher asks varieties of questions where students higher order thinking skills are developed. Concept formation is also developed in this stage. students are formally introduced to a concept by the teacher. Through a series of questions and discussions, students actively apply and communicate their understanding of the concept, further developing their critical thinking reasoning and communication skills.

Application: This step is a very challenging step where students are given real life problem solving activities and situations where there is a direct link to theory as well as practicality, allows students to exercise their newly acquired knowledge in the form of a worksheet, reflective questions, and challenging problems (analytical thinking).

Assessment: Students learning is measured and also feedback is given for the further improvement. Application-based questions to be given.