Charging Methods

Charging BY induction

Charging a Body: We know that all bodies are made of atoms/molecules which contains both positive and negative charge. In general the bodies are electrically neutral which means that the amount of positive or negative charge present in the body is exactly equal. To charge any body two methods can be used [a] Charging by conduction [b] Charging by induction Charging by conduction: In charging by conduction, the boy which is to be charged is placed in physical contact with some other body. This can be done in two ways [a] charging by contact [b] charging by friction Charging by contact: In charging by contact, a neutral body is placed in contact with the charged body. Charge is transferred from charged body to the uncharged body till some equilibrium condition is achieved [equilibrium condition is the common potential]. For e.g. if a positively charged body A is placed in contact with the neutral body B, electrons will be transferred from the neutral body to the charged body till both acquire a common potential. This concept is analogous to the transfer of heat between two bodies at different temperature, heat transfer takes place till a common temperature is acquired. This phenomenon can be used in case of bodies which conduct. Charging by friction: we know that in an atom the inner electron are tightly packed an outer electrons are comparatively loosely bound. Thus, lesser energy is required to free electrons in the valence shell of the atom. When we run to two bodies the work which we do in rubbing removes the electrons from the valence shell of atoms in body in which they are loosely bound. These free electrons are transferred to the other body. The body which gains electrons acquires negative charge and the body which looses electrons acquires positive charge. The net charge on this system remains same. For e.g. if we rub our shoes on a carpet our body gets charged, thus if we touch a metallic door handle the charge is transferred to handle and we experience a shock. Charging by induction: The phenomenon in which the body gets charged without placing it in direct contact with any other charged body is called charging by induction. As shown in figure two neutral metal spheres are in contact, both supported on insulating stands. When a negatively charged rod is brought near one of the spheres but without touching it, as in [b], the free electrons from the metal are repelled and drift slightly away from the rod, towards the right. This leaves a positive charge on the left sphere. This negative charge on right sphere and positive charge on left sphere are called induced charges. These induced charges remain on the surfaces of the sphere as long as the rod is held nearby. [When the rod is removed , the electron cloud in right moves to the left and original neutral condition is restored.] But suppose the electrons are separated slightly as shown in [c] while the plastic rod is nearby. If the rod is now removed the opposite charges on two spheres will attract each other. When the two spheres are separated by large distance each of the two spheres will have uniform

 

Coaching Center Menace

From my experience of teaching the students of XIth and XIIth from past many years, I can observe an undercurrent of dissatisfaction in the students/teachers and parents [i.e. all three communities involved in Child's education] After discussing the issue with all three concerned, I would like to visualize the issue from everybody’s point of view.

Students: The main issues concerning the students are:

• No synchronisation between school preparation and the that for competitive examination
• The teachers in schools are not competent enough to prepare them for the entrance examinations conducted at all India level
• Lot of pressure on the students fro school to perform well in board even at the cost of bad performance in entrance examination
• Parents are not able to understand the practical problem of students in dealing with vast syllabus
• Lack of time as after school and coaching classes they are generally very tired and can’t study much.

Teachers: Discussing the same issue with the teachers involved in school education, their main concerns are

• Students are not listening to what is being taught in the School as they have already covered the syllabus or will cover the same at coaching classes
• Gross irregularity in attending the school and the sole purpose of coming to school is for getting the minimum number of lectures required to sit for Board examination
• No incentive for hard working teachers if they work as hard as coaching classes tutors to satisfy the needs of the students
• Their performance is solely judged by the performance of overall class in the Board examination and schools don’t encourage them to maintain balance in teaching
• Duration of class is 35-40 minutes which is not at all sufficient for Physics or Chemistry class as with thorough discussion of articles the rate at which syllabus is to finished will be retarded.

Parents: Although they are not directly involved in teaching or learning process thier concerns are genuine. The main concerns of parents are

• Why coaching is essential in all the science subjects even if the child is going to best school in the city
• They are spending lot of money on coaching and the student is still not able to perform well in school examinations
• Nobody [school/coaching class] is ready to take the responsibility of non performance of the student. Thus, willingly or unwillingly the pressurize the child to work harder.

Solution To The Problem

After analyzing the problem of all concerned i can’t think of an ideal solution to the problem. But still i want to suggest two possible ways to move forward

Solution :1

Schools can outsource the coaching work to some group of local teachers who are competent enough for both board and competition preparation. They can help students prepare for both board and competitive examination in the school itself. The performance of teachers should be judged not only by the score of student in board but also his/her rank in competitive examination.This can be done on profit sharing basis with the school

Solution:2

The teachers in the school are competent enough to prepare students from both and competition point of view. This can be done by engaging good teachers at good salary.

 

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