BEFORE THE MADURAI BENCH OF MADRAS HIGH COURT

DATED: 02/08/2012

Coram

THE HONOURABLE MR.JUSTICE B.RAJENDRAN

W.P.(MD)No.9129 of 2012

and

W.P.(MD)No.9094 of 2012

and

M.P.(MD) Nos.1 and 1 of 2012

Augustine David ... Petitioner in

W.P.(MD)No.9126 of 2012

Minor J.P.Febin Samuel

Rep. by his father and natural

guardian C.Janet Sam Mohan Roy,

S/o. V.Chelliah,

"SMILES",

No.191-223-1, Carmel Mount Road,

Nagercoil,

Kanyakumari District. ... Petitioner in

W.P.(MD)No.9094 of 2012

vs.

1.The Government of Tamil Nadu,

Rep. by its Principal Secretary,

Department of School Education,

Fort St. George,

Chennai - 600 009.

2.The Secretary,

State Board of Higher Secondary School Education, Chennai.

3.The Director of School Education,

College Road, Nungambakkam,

Chennai.

4.The Director of Government Examination,

D.P.I. Campus, College Road,

Chennai - 600 006.

5.The Director,

Directorate of Medical Education,

Chennai. ... Respondents

COMMON PRAYER

Petitions filed under Article 226 of the Constitution of India to issue a Writ of Mandamus directing the respondents 1 to 4 herein to award one mark to the petitioner for Question No.25 and Question No.10 of Part III Physics Examination respectively and consequently direct the fifth respondent to revise the petitioners' rank for admission to the M.B.B.S. course and admit them in the appropriate college as per the revised rank.

!For Petitioner ... Mr.R.Subramanian

^For Respondents... Mr.

:COMMON ORDER

***********

Since the issue involved in both these writ petitions is one and the same, both the cases are taken up together for final disposal and a common order is being passed.

2. In both the writ petitions the challenge is to the answer given in respect of question No.25 (B series) and No.10 (A series) of Part III Physics Examination is wrong and thereby the petitioners have lost one mark for the questions. According to them, the question and the key answer is given as follows:

In the photoelectric phenomenon if the ratio of the frequency of incident radiation incident on a photosensitive surface is 1:2:3, the ratio of the photoelectric current is:

a) 1 : 2 : 3 b) 1 : 2 : 3

c) 1 : 4 : 9 d) 1 : 1 : 1

The answer given by the petitioners is a) 1 : 2 : 3 The answer as per key is d) 1 : 1 : 1

3. The main contention of the petitioners is that if the key answer is to be held correct then the theory would be photoelectric current is independent of frequency. But, according to them, they have been taught from 10th standard that the photoelectric current depends upon frequency. They would also contend that as per the graph which is given in page No.224 in figure 7.12 would reveal that the variation of photoelectric current with frequency and therefore the photoelectric current increase with frequency. As per the graph which is given in Page No.54, figure 7.4, the saturation current alone is independent of frequency. But, it is not mentioned in the question as saturation current. Therefore, according to them that before reaching saturation, the photoelectric current increases with frequency. As there was an ambiguity in the question and the key answer, on getting the answer sheet, they have made a representation dated 27.06.2012. Since they did not get any action as that would entitle them to get one more mark in the Physics subject and if one more mark is obtained their rank will differ thereby they will get medical seat even in Government quota. Since this has not been done, they have come forward with these writ petitions seeking for the above said reliefs.

4. In this connection, the learned Special Government Pleader took notice and submitted a written explanation for both the cases. According to the experts, they have opined as follows:

4.1. In Einstein's Photo electric equation

hy = hy o + 1/2mv2

It is clearly and unambiguously understood that the threshold frequency Yo being constant for a photo sensitive surface, when the frequency of the incident radiation increases, only the kinetic energy of the photo electron increases. Therefore, when the frequency of the radiation increases there is no question of the number of photoelectrons increasing. If it is so, the petitioner not only challenges the question but also the very fundamental meaning of Einstein's photoelectric equation.

4.2. They would further opine that in photoelectric emission Einstein's photoelectric equation is verified experimentally and accepted universally. According to him, when one photon is incident on the photoelectric surface one electron is ejected. Even if the frequency of the photon is doubled only one electron will be ejected but with a grater velocity. Photoelectric current depends on number of photons incident on the surface increases number of electrons ejected increases. Therefore, the photoelectric current depends on intensity of the radiation and not on the frequency. If the photoelectric current depends on frequency, the validity of Einstein's equation is challenged. Thus, the petitioner wrongly understood the very basic concept of Einstein's photoelectric equation.

4.3. They would opine that according to the petitioner "photo electric current depends upon frequency" (page 36 of Matriculation physics Book). This means that the photo electric emission is possible only when the incident frequency is greater than the threshold frequency of the surface. This point is also clearly reflected in the question.

4.4. Further they would opine that the petitioners have not clearly understood the meaning of the stopping potential. Stopping potential is not a directly linked parameter in photoelectric effect. The question in the question paper relates the incident frequency and the strength of the photoelectric current and it does not relate the stopping potential and photoelectric current as claimed by the petitioners. Hence, the argument put forward by the petitioners is not valid.

4.5. They would further opine that the question No.25 in B series and 10 in A series is properly worded and it is clearly related to the law of photoelectric emission and Einstein's photoelectric equation. According to the revised edition XII std physics text book Volume II, Page No.52, the number of photo electrons emitted per second is proportional to the intensity of the incident radiation. Photo electric current increases linearly with the intensity of incident radiation. This is reflected in law II. Further, for a given intensity of incident radiation and for constant frequency, the number of photo electrons emitted from the surface or the maximum number of photo electrons emitted from the surface are one and the same and they are equal. If the frequency alone is changed, the number of photo electrons emitted does not change. Hence, the strength of the photo electric current is independent of frequency.

4.6. Finally, they would opine that the question is not creative and it is a direct implication of Einstein's Photoelectric equation and it is from the text matter itself. In support of the above argument they have given a question and answer from the CBSE text matter (Move fast with physics, Class XII by S.L.Arora)

How is the photo electric current affected by increasing the frequency? (CBSE OD 06)

The increase of frequency of incident radiation has no effect on the photoelectric current. This is because the incident photon of increased energy cannot eject more than one electron from the metal surface.

5. Therefore, the respondents would only contend that both the question as well as the answer is correct. In this connection, they would submit that confirmation of the key to the questions is done after various stages of the examinations.

6. Heard both sides.

7. The main ground of attack by the petitioner in both the cases is that the question No.25 (B series) 10 (A series) is ambiguous. In fact, they would mainly contend that the key answer given is totally wrong for the reason that what they were made to read and understand was totally different from the question that as per the key answer which has been provided. According to them, even in 10th standard book they were made to read and know that the photo electric current depends upon frequency and in 12th standard book they would mainly contend that the variation of photo electric current with frequency is explained with a graph and in the graph it is clearly stated the photo electric current increases with frequency. In another graph it is stated as the saturation current alone is independent of frequency. But when the question paper does not reveal the saturation current would mean that before reaching saturation the photo electric current increases with frequency. Therefore, there is a ambiguity in the question and key answer. Therefore, they have made a representation dated 27.06.2012 to consider their case. Since, that has not been answered, they have come forward with this writ petition.

8. In this connection, they would contend that if the mark is given for this question treating this answer is wrong, whereas the answer has been given wrong, they would be place in a better position and they would be getting a seat in the medical college even in Government quota.

9. The respondents have given a detailed reply though not in the form of counter but in written explanation in which it is clearly contended that the question and answer is absolutely correct. In fact, in the expert opinion, the question is in correlation with the Einstein's theory and formula (hy = hy o + 1/2mv2). They would also clearly explained that what is the actual meaning of the questions. In fact the answer is given point by point which read as follows:

"In photoelectric emission Einstein's photoelectric equation is verified experimentally and accepted universally.

According to him, when one photon is incident on the photoelectric surface one electron is ejected. Even if the frequency of the photon is doubled only one electron will be ejected but with a grater velocity. Photoelectric current depends on number of photons incident on the surface increases number of electrons ejected increases. Therefore, the photoelectric current depends on intensity of the radiation and not on the frequency. If the photoelectric current depends on frequency, the validity of Einstein's equation is challenged. Thus, the petitioner wrongly understood the very basic concept of Einstein's photoelectric equation.

According to the petitioner "photo electric current depends upon frequency" (page 36 of Matriculation physics Book). This means that the photo electric emission is possible only when the incident frequency is greater than the threshold frequency of the surface. This point is also clearly reflected in the question.

The petitioner has not clearly understood the meaning of the stopping potential. Stopping potential is not a directly linked parameter in photoelectric effect. The question in the question paper relates the incident frequency and the strength of the photoelectric current and it does not relate the stopping potential and photoelectric current as claimed by the petitioners. Hence, the argument put forward by the petitioners is not valid.

The question 10 in Section A is properly worded and it is clearly related to the law of photoelectric emission and Einstein's photoelectric equation.

According to the revised edition XII std physics text book Volume II, Page No.52, the number of photo electrons emitted per second is proportional to the intensity of the incident radiation. Photo electric current increases linearly with the intensity of incident radiation. This is reflected in law II.

For a given intensity of incident radiation and for constant frequency, the number of photo electrons emitted from the surface or the maximum number of photo electrons emitted from the surface are one and the same and they are equal. If the frequency alone is changed, the number of photo electrons emitted does not change. Hence, the strength of the photo electric current is independent of frequency.

The question is not creative and it is a direct implication of Einstein's Photoelectric equation and it is from the text matter itself.

In support of the above argument they have given a question and answer from the CBSE text matter (Move fast with physics, Class XII by S.L.Arora)

How is the photo electric current affected by increasing the frequency? (CBSE OD 06)

The increase of frequency of incident radiation has no effect on the photoelectric current. This is because the incident photon of increased energy cannot eject more than one electron from the metal surface."

10. In fact, this reply is prepared by the three experts. They have also produced textbooks of 12th standard under the heading Einstein's photo electric equation. We find what was taught to them is as per the textbook 23.9 (iv) An increase in the frequency of the incident radiation increases the energy of the emitted electrons as given by Einstein's equation. An increase in frequency does not increase the number of photoelectrons. This means that the photocurrent will not increase because the photocurrent depends simply upon the number of photoelectrons. Thus, the increase in frequency has no effect on the magnitude of photocurrent. Then the graph has been explained by the experts as "the intensity affects the number of electrons, and the frequency affects the kinetic energy of the emitted electrons" and "the number of electrons (i.e. the electric current) is proportional to the intensity and independent of the frequency of the incident radiation above the threshold value of V0(no current is observed below v0)". Further they have explained that "the number of electrons emitted per second (i.e. the electric current) is independent of frequency and increases linearly with the light intensity."

11. From the explanation given by the experts and from the text book itself it is very clear that the question and answer given by the respondents is correct. In this connection, they have also explained that the confirmation of the key to the question is done after various stages of the examination. The stages are stated as follows:

(i) The experts committee constituted by the Directorate of Government Examinations, first looks into the complaints related to the question paper, Teachers, Students and the Public in general. After a careful scrutiny of all complaints / grievances, the key will be prepared with the authenticity of the text book and the experts opinion.

(ii) Based on the key prepared as above the Chief Examiners, all over the State, evaluate the answer scripts on the 1st day of evaluation. If any discrepancies is found in the prepared key at this stage, then again the question and the key undergo scrutiny.

(iii) From the second day onwards of the evaluation, the Assistant Examiners evaluate the answer scripts and the report for errors if any, in the questions as well as keys. In this stage too appropriate action will be taken on the reported complaint.

(iv) During these period of evaluation, the experts committee also looks into various complaints if any, or reported by the media, news papers and the public.

12. Even as per the opinion produced by the petitioner himself some of the Professors have only stated that when the textbook in page 224 mentions photo electric current increases with the frequency, it would be true that the incident of frequency is less than the threshold frequency.

13. They would further contend that about the threshold frequency photoelectric current depends on intensity of incident radiation. Therefore, the experts would only say that the answer key given by the respondents as 1:1:1 will be true when frequency is greater than the threshold frequency. He would finally conclude that since there is no mention about threshold frequency both answers can be construed as correct. They have not given any opinion that the answer is wrong. They would only conclude that the word threshold has not been mentioned. Whereas from the explanation of the respondents and text book it is very clear that the key answer given is correct. Under those circumstances, this Court does not find any reason to interfere especially when there are various stages made by the respondent authorities to check the correctness of the question and answers and rightly nobody else has so far questioned the same even at this point of time and there is no ambiguity. Hence, the both the Writ Petitions are liable to be dismissed.

In the result, the writ petitions are dismissed. Consequently, connected miscellaneous petitions are dismissed. No costs.

srm

To

1.Secretary,

State Board of School Examinations (Higher Secondary), Department of School Education,

Chennai.

2.Director,

Directorate of Government Examination,

Chennai.

3.Secretary,

Selection Committee,

Directorate of Medical Education,