Here is a summary of the questions which has possibly been set wrong (I have given details below) or numerical answer types whose answers have been given incorrectly as per the declared answer sheet.
Q8. The magnetic field also has a odd parity. Not “E and A only”. Since that choice (or “none of the above”) isn’t given, clearly the question has been set wrong. See here.
Q3. The Stern-Gerlach experiment evidenced space quantification of angular momentum. The Zeeman effect evidenced the existence of electron spin. That choice isn’t given, instead answer sheet gives the opposite as the correct answer. See any good text on quantum mechanics. eg “Quantum Mechanics 2nd edition, Bransden, Joachain” page: 37 and 38. To avoid any ambiguity, Its the S-G experiment which evidences space quantization (of both spin and orbital angular momentum). But Zeeman effect evidences electron spin only. It was the anomalous Zeeman effect which had led to the discovery of electron spin.
There are also two NAT type questions which seems to be way off in the correct responses as per the exam conducting body. But the calculations shows somebody missed something somewhere. They are questions 48 and 49 according to the uploaded answer sheet and question paper. I have performed the detailed calculations in this pdf file: gatephysics_2018.
Altogether this is 6 marks and 2/3 marks for the Q3 and Q8 if they have been deducted wrongly. So, 6+2/3 marks. I haven’t been able to find any more lapses although it was very tempting to feel so.
I think the above question asked in GATE 2018 (physics) is wrong.
Any vector has two components. The component perpendicular to the parity axis has even parity and the parallel component to the axis has odd parity.
The opposite is true for axial vectors.
E, A vectors.
B, L axial vectors.
The correct answer per gate exam body is E, A. Why not B and L? It’s an arbitrary situation and perpendicular components of these fields will have odd parity.
So the question since it does not specify the direction might be wrong. Unless I’m missing anything. What’s your idea ?
I am adding one relevant page for why the answer might be wrong. (A question is wrong, when all possible answers given are, wrong. That seems to be the case here.) For detailed answer and any other relevant page, check here. [Prof. S. Errede’s handouts. UIUC]
According to this lecture note from a famous university (UIUC) among E, B, L and A except L all others have odd parity. L doesn’t as its made from cross product of two vectors (r and p) which both have odd parity. There are several ways to see why B has odd parity as well. One is to see it as B = curl A. A has odd parity and grad operator has even parity. Check page 5 of the linked note from UIUC.
So except L all others have odd parity. [E, B and A]. Putting the phrase “only” makes the question erroneous. Because e and A pair is right but its not the only ones among the given vectors which has odd parity.
Nuclear and particle physics through Scilab. More…
The concurrent election in Odisha just drew to a close and I did an analysis on the results available tentatively. Notice that there is no visible errors here even if I eg adjusted 854 to 850 and so on. If you add up the % figures they add to 100% perfectly — I simply did the calculation and applied no tricks, that means there is some simple pattern in the data which is the reason I made this post. More…
Finally I am successful in calculating pi value — less than 0.3% error, by using random number generation. Although my computer needs some fixation on its compiler or path definition etc, there are very good online compilers which helps in testing and running c++ codes: try the given link.
Computing the value of pi using std::rand()
Enter number of trials: 10000
Enter number of random (x,y) points per trial: 10
pi = 3.14376 +- 0.00519107
average – exact = 0.00216735
CPU time = 0.004027 secs
Here is the code I found by searching a good deal on the web. Yes I did tinker around but only because my own compiler (Turbo C++ on windows 10, 64 bits) was throwing some exceptions on the included headers.
using namespace std;
double pi_estimate(const unsigned long points) More…