Our Education System

The center around which our education is moving is wrong. Our educational system is revolving around ambition. We are taught a race to get ahead of everyone.

Even in a small child learning in Kindergarten we are creating an anxiety about coming first in the class. We are creating competition in him. Competition is a kind of fever. When you are feverish there is a rise of energy. You can run faster, you can do things, which you ordinarily would not be able to do. This fever of competition gets hold of the children. They start thinking about becoming a Doctor, an Engineer, an I.A.S., a Pilot etc., without taking care of their aptitude and without acknowledging their capacity or capability.

Even after they come out of the field of education that fever persists. They want to build a bigger house, have a bigger shop, reach a higher position. From being a junior clerk, they want to be the head clerk; from being a deputy minister they want to become a minister and then the prime minister. In this mad race the whole peace, energy and capability in their lives get destroyed. What do they achieve in the end? They reach nowhere. So far in the world nobody has got ahead of everybody. But we are still teaching our children to come first. They remain in the race throughout their life and waste it.

We go on saying to people, “Do not be envious, violent and jealous,” but our whole education is rooted in jealousy. We point to one child and say to the other, “See how intelligent he is, and how dull you are. Be like him!” Thus we create envy and jealousy. This poison of envy goes on flowing through the mind and veins of our children, saps their creative energy and causes them the cancer of competition. This is a fundamentally wrong teaching. If we want to create a new world we will have to change this center and create a new center. What can this new center be?

The center of education should be love. To learn anything, humility and egolessness are required. Not competition with a fellow student, but love, sincerity and delight in the subject to be learned are required.

It is better that we teach love for mathematics, rather than competition with others learning mathematics. Everything can be learned when we have love for that thing; then only is it possible to learn. But we are not taught what love is. Our education has nothing to do with love. So what actually happens is that if you have studied literature in the university, after coming from the university you do not continue to learn literature, because it has harassed you and bored you a lot. If you have learned poetry in the university, your love and joy for poetry in life will have already been destroyed because it was studied during the race of egos, studied only to get through the examinations and studied to come first. No love for poetry was really created.

Therefore, in fact, it happens that our education destroys our genius. We study mathematics aiming at 100 out of 100 so that we may create an unbreakable record. Mathematics is the language in which nature communicates with intelligent living beings and what we do with it, we make it such a boring subject that most of the students feel afraid of it. This subject conveys eternal truths but many students start hating it because of the syllabus, which is practically useless.

Same is the situation with all other subjects. The entire approach to education needs a complete overhaul.

Photocell - Practical application of Photoelectricity

Explain the functioning of a photocell. Give its two uses.

A photocell is a practically useful device based on the photoelectric effect. It enables us to change light energy into electrical energy. Now-a-days photocells that work with ‘invisible lights’. like infrared radiations, ultraviolet rays, etc., are also available.

The early photocells were of the vacuum tube variety. Such a photocell consisted of an evacuated ‘bulb’ (made of glass for ordinary visible light and, of ‘quartz’ for ultraviolet radiation) which ‘contained’ a suitably supported and appropriately sensitive metal plate (to act as the cathode) of a semi-cylindrical shape.

The ‘metal plate’ chosen was such that its threshold frequency was well below the frequencies of light’ to be used with the photocell. This was achieved by coating the metal surface with a suitable photo sensitive coating like potassium oxide, cesium oxide or rubidium oxide, etc. The evacuated bulb also had a thin rod of platinum or tungsten to serve as the anode. When light was made to fall on the ‘cathode’. there was an emission of photoelectrons from its surface. These photoelectrons were attracted towards the anode (maintained at a positive potential with respect to the cathode) and hence photoelectric current flowed in the external part of the cathode—anode circuit. We are thus, able to get an electric current (electrical energy flow) from light energy.

What are the uses of a Photocell.?

(I) Photocells are used in counting and automatic control systems.

(ii) They can be used to control furnace temperatures and to study astronomical phenomenon like
temperature and spectra of Stars.

Photoelectric Effect - Conceptual Problems - 02

Photoelectric Effect

What is threshold frequency?

The threshold frequency (vo) is the minimum frequency of the incident light, for which photoemission is possible, from a given metal surface. It equals (Wo/h), where Wo  is the work function of the metal concerned

Does threshold frequency depends on the nature of the emitter?

Ans Yes ,each emitting surface has a threshold frequency characteristic of the ‘emitter’ concerned.

What is stopping potential?

Ans The minimum value of the negative potential needed, to completely stop the flow of the photoelectric current, is known as the stopping potential. It depends on the frequency of the incident light, for a given emitter.

The stopping potential for some material is 1.2 V. What is the energy range of the emitted photoelectrons?

The range of energies of the emitted photoelectrons will be from 0 to 1.2 eV.

The intensity of incident radiations in a photoelectric experiment is doubled. How the stopping is potential affected?

The stopping potential will remain unaffected because it does not depend on the intensity of the incident light

If the intensity of the incident radiation in a photocell is increased, how does the stopping potential vary?

Stopping potential is directly proportional to frequency of the incident radiations only. So, stopping potential remain unaffected by increase in intensity of incident radiation.

If the intensity of the incident radiation on a metal is doubled, what happens to the kinetic energy of the emitted photoelectrons?

There is no change in the kinetic energy of the emitted electrons. This K E. is independent of the intensity of the incident radiation as long as its frequency remains the same.

The frequency of incident radiation is greater than threshold frequency in a photocell. How will the stopping potential vary if frequency is increased, keeping other factors constant?

Stopping potential will get increased.

The wavelength of electromagnetic radiation is doubled. What will happen to the energy of
the photons?

Thus, on doubling the wavelength, the energy of the photons will be halved.

Is photoelectric effect an instantaneous phenomenon” ?
Yes, the photoelectric effect is an instantaneous phenomenon with (practically) no time delay between the incidence of light and the start of the photoelectric emission.

Note: Few of the above questions are similar. They are here to show the variations of  language in different sets of question papers.

Important features of the phenomenon of Photoelectricity

What are the salient features of the phenomenon of Photoelectricity?

Detailed quantitative investigations on the phenomenon of  Photoelectricity show that this phenomenon has the following salient features:

(i) When light (of suitable frequency) shines on a (sensitive) metal surface, the latter emits electrons.

(ii) The phenomenon of photoemission is an instantaneous phenomenon. We start getting emission of photoelectrons as soon as’ light falls on the metal surface.

(iii) The photoelectric current obtained with a given light (light of a particular frequency) is directly proportional to the intensity of the incident light.

(iv) All the emitted photoelectrons do not have the same energy. There is an energy distribution from zero to certain maximum value, say Emax, amongst the emitted photoelectrons.

(v) The maximum energy of the emitted photoelectrons - for light of a given frequency is independent of the intensity of the incident light.

(vi) The maximum energy of the emitted photoelectrons is found to be directly proportional to the frequency of the incident light (vii) For each emitting surfaces, there is a (critical) minimum frequency of the incident light below which photoemission from that surface does not take place. We call this minimum frequency as the threshold frequency of the given surface.

(viii) We get instantaneous photoemission for incident light frequencies greater than the threshold frequency. This happens even at very low intensities. However, if the incident light frequency is less than the threshold frequency, photoemission does not take place.

(ix) For a given frequency of the incident light, the photoelectric current becomes zero at a particular (minimum) value of the negative potential of the anode with respect to the cathode. We call this potential as the stopping potential for that frequency.

(x) The values of the stopping, potential (V) for a given surface, are directly proportional to the frequencies of the incident light.

(xi) The stopping potential V/s frequency graphs for different metals all have the same slope but different intercepts on the frequency axis as shown in Fig. alongside, It means that the graphs for different metals are alt straight lines parallel to each other.

Photoelectric Effect - Conceptual Problems - 01

Photoelectric Effect

 

 

 

What do you understand by photoelectric emission?

The emission of electrons, by metal surface when light falls on them, is known as photoelectric emission and the phenomenon is known as photoelectric effect.

How was the phenomenon of photo-electricity discovered?

The initial discovery of the phenomenon of photo electricity can be said to have been made by Hertz. He observed that the spark. across the gap of his ‘detector, passed much more easily when ultraviolet light was allowed to fall on it. The phenomenon was later on formally discovered by Hallwachs. He discovered that when (suitable) light is allowed to fall on the cathode of an evacuated tube, current flows towards the anode. No current would flow if the anode was irradiated with light. This indicated that negatively charged particles can get emitted from the cathode when it is irradiated with (suitable) light.

Explain how it was established that photo particles are negatively charged electrons?

The identity of the photo particles with electrons was suspected when it was observed that the photo particles are also negatively charged (like the electrons). The exact identity was established when Lenard, through his detailed quantitative measurements, showed that the (e/m) of the photo particles was the same as that of electrons. All the photo particles Irrespective of the nature of the metal of the cathode or the frequency of the irradiating light always had the same value of elm as those of the electrons.

Light from a bulb is falling on a wooden table but no photoelectrons are emitted, Why?

Wood is a bad conductor (insulator) and hence, contains no free electrons.

Why is alkali metals most suited as photo- sensitive materials?

The work function for these metals, being very low, even lights of low frequency can cause photo-emission from them.

Do all the photoelectrons emitted from a metal surface possess the same energy?

No, there is an energy distribution amongst the emitted photoelectrons, with their energy ranging from (zero to a certain maximum value = h (v - vo) characteristic of the frequency of the incident light.)

Does the maximum energy with which electrons is emitted from a metal surface depend
upon intensity or frequency of the incident light?

The maximum energy of the emitted photoelectrons depends on the frequency but not on the intensity of the incident light.

Is photoelectric emission possible at all frequencies? Give reasons for your answer.

No: photoemission is possible only for a certain minimum frequency value (called the threshold frequency, represented by 'vo' ). This is because the incident photons must have at least the minimum energy equivalent to the work function W0 of the metal.

 
Why photoelectric effect cannot be explained on the basis of wave theory of light?

Electro-Magnetic Waves theory’s failure vis-à-vis Photoelectric effect;

The Electro-Magnetic Waves theory could not explain the experimental results on photoelectricity. This is because as per the Electro-Magnetic Waves theory, it is the forces, exerted by the electric field of the incident light beam, that bring about an increase in the energy of the free electrons present in the metal. However the, above mechanism of gain of energy by the free electrons from the incident light beam, does not fit in with the observed features of photoelectricity This can be seen as follows:

1) The energy of the incident radiation - as per the Electro-Magnetic Waves theory must be regarded as smoothly and evenly distributed over its associated wavefront. Hence, each electron would intercept only an insignificantly small amount of energy and would require a finite time (hours, days or weeks) to accumulate enough energy to escape from the metal. Experimentally, however, we observe that electron ejection commences without (any noticeable) delay.

2. The classical wave theory was unable to account for the existence of the threshold frequency. There should be no reason why sufficiently intense beam of low frequency radiation would not be able to produce photoelectricity, if low intensity radiation of higher frequency could produce it.

3. On the classical theory, we expect that light of high intensity, i.e.. consisting of strong fields.
would give higher kinetic energy to the liberated electrons. This, however, does not happen. Also the electron’s energy should not depend particularly on the light frequency. But it does. It is obvious: therefore, that the photoelectric effect cannot be explained on the basis of the classical Electro-Magnetic Waves theory of light.
 

Doctor's Day - Absence of regulations, responsibility and firm laws in the field

July 1 is seen as Doctors' Day in India to respect the fanciful doctor, Dr B C Roy whose conception & passing commemoration falls on that day. The day is a chance to bring issues to light about the specialist's part in our every day lives - a day when individuals the nation over recognize the dedication and commitment of the restorative and health awareness clique towards public opinion. It is likewise a critical day for specialists themselves as it gives them a chance to think about their vocation & help themselves to remember morals of prescription.

India is novel as in patients worship their specialists lion's share of whom are earnest, legitimate and moral. Notwithstanding, because of deceptive practices by a little rate of specialists (numbers expanding exponentially however), confidence in the restorative calling, which once was viewed as the noblest of all, has gotten hammered. It is unequivocally this misfortune of confidence that has brought about patients 'looking' in the trust of discovering a 'decent specialist'. Unfortunately, in this try, there is a plausibility that patients may exceptionally well wind up with the wrong decision substantiating the view that discovering the right specialist in India is a lottery!
Ravenousness, absence of regulation, absence of responsibility, absence of firm laws and an indulgent pop culture has permitted unholy nexus between specialists, doctor's facilities, demonstrative focuses & pharma industry. Subjecting patients to unnecessary examinations, techniques & surgeries is getting extremely regular. The patient trusts and spots his life in the hands of specialist. On numerous events, the patient uncovers classified data to the specialist which he/she may or may not have talked about with his/her companion or relative. In no other calling does the individual place so much trust and confidence. In a few districts, especially in rustic India, the specialist is compared with God. The specialist is, along these lines, compelled by a sense of honor to have a more elevated amount of good implicit rules than those in different callings and must comprehend that he/she is in an exceptionally favored position.

Morals & formal preparing in exploration approach has a secured place inside the therapeutic educational program all through the western world. There is a dire requirement for both these segments to end up part & bundle of the medicinal educational program in India. The Medical Council of India Act has laws set up to immovably manage specialists who have veered off from the code of morals. The administration of India must guarantee that these laws are strictly authorized. The idea of 'Family Physician' is pretty much wiped out in India. The powers that be must resuscitate this idea. We, as a nation, must switch from convention of rehearsing the more forceful "Assimilated prescription" to "British pharmaceutical", which is much more traditionalist and proof based, which would go far in lessening dishonest practices.

It is basic for both patients and specialists to cooperate on re-securing a percentage of the lost trust, and genuinely, there could be no preferable day over Doctors' Day to strengthen the exceptional relationship between the specialist and patient. On the event of Doctors Day, I might want to help myself to remember a paramount segment of Hippocratic Oath - and that is to 'keep the benefit of the patient as my most elevated necessity'.

Engineering Medical Entrance Exams

Success in both the Boards and engineering entrance exams is no longer an “either or” situation. In reality, preparing for, and succeeding in both the Board exams and Engineering entrance tests are complementary to each other. This is because both test underlying knowledge in Physics, Chemistry and Mathematics. The only difference is that while the Board Exams require students to write standard answers, engineering entrance tests emphasize on the application aspect of the same knowledge base. Rajesh Verma Classes is the ideal place for all the ENGINEERING aspirants preparing for Entrance Tests of IIT-JEE /AIEEE / DCE / IP / BITSAT / CEE etc. It is this sense of complementarity, which is the core ideology behind our Engineering test-prep + Boards program. Designed and created by me, the course curriculum of Rajesh Verma Classes effectively delivers the goods for both sets of exams. As a student aspiring for a career in engineering and technology, alongside the responsibilities of faring well in Class XII, you must also be feeling a little apprehensive about being able to judiciously handle studying for both engineering entrance and Board exams. All the students face a dilemma at this point of time. It is regarding whether to spend the precious and limited time in hand in studying for the crucial Board exams; or focus instead on preparing for engineering entrance exams, like IIT-JEE /AIEEE /DCE / IP / BITSAT / CEE etc. To address the needs of students for CBSE XII Boards, my program focuses on:
Building concepts for each of the topics through classroom sessions
Perfecting the answer writing skills for CBSE Boards through regular assignments, practice exercises and class tests .
For Engineering Entrance Tests preparation , the program trains students on:
How to apply the concepts learnt for solving objective type problems.
Improving problem solving capacity for tougher/ tricky problems up to IIT-JEE /AIEEE /DCE / IP / BITSAT / CEE level questions.
How to manage time and accuracy level in taking objective test, which is based on the relative performance rather than absolute performance.
The special features of the Engineering + Boards test prep program are:
The program starts from First week of April with a view to utilize the summer vacations effectively, and continues till May.
Integrated course structure, which prepares students simultaneously for both the exams.
Exhaustive Study Material – Separate material for Boards and Engineering preparation.
Weekly Tests and regular feedback on performance.
Regular parent-teacher interaction
Crash Courses Start in March. Visit:(CRASH COURSES-2008)

Caution: I have observed that most of the students tend to ignore the importance of studying the regular textbooks prescribed by CBSE for 11th and 12th classes. I strongly suggest that the first step in the preparation for IIT-JEE /AIEEE /DCE / IP / BITSAT / CEE etc. is to have a good grasp of all the subject matter that is there for the 11th and 12th class exams. A student cannot think of reaching out to higher level of learning the subject and comprehend the intricacies of the tricky questions without an in-depth study of the regular TEXT BOOKS. Subject-matter discussed in the textbooks gives the broad theoretical frame-work that is needed for the competitive exams.

If you aim for the stars, moon should not be a problem. Preparing for IIT-JEE automatically prepares you for AIEEE / DCE / IP.
I suggest Engineering aspirants to meet me in person along with parents for proper career-counseling.