A particle is moving in a circular path of radius a under the action of an attractive potential \[ U=-\frac{k}{2r^{2}} \]
. Its total energy is :-
(1) \[ -\frac{k}{4a^{2}} \]
(2)\[ \frac{k}{2a^{2}} \]
(3) Zero
(4) \[ -\frac{3}{2} \frac{k}{a^{2}} \]

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Solution to JEE Mains 2018 Physics Q3

Q3: Two masses m 1 = 5 kg and m 2 = 10 kg, connected by an inextensible string over a frictionless pulley, are moving as shown in the figure. The coefficient of friction of horizontal surface is 0.15. The minimum weight m that should be put on top of m 2 to stop the motion is :

(1) 18.3 g
(2) 27.3 kg
(3) 43.3 kg
(4) 10.3 kg
Ans:
Motion will stop when pull due to m1 will become equal to the force of friction due to mass (m1+m) and surface.
\[ m_{1}g=\mu (m_{2}+m)g \]
\[ m_{1}=\mu (m_{2}+m) \]
\[ 5=0.15(10+m) \]
m=23.3kg
Hence the nearest solution is (2).
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Solution to JEE Mains 2018 Physics Q2

\[E \href{javascript:alert("Einstein says so!")}{=} mc^2\] Q2. All the graphs below are intended to represent the same motion. One of them does it incorrectly. Pick it up -
------------------------------------------------------------------

----------------------------------------------------------------------

----------------------------------------------------------------------------

Ans:
(a)


\[ v^{2}=u^{2}+2as \] के अनुसार एवं (c) और (d) के अनुसाय यह भी उस motion को दिखा रहा है जो (c) और (d) में दिखाई गई है.
--------------------------------------------------------------------------
(b)


Correct distance vs time graph is following:

------------------------------------------------------------------------
(c)
\[ S=ut+\frac{1}{2}at^{2} \]

(d) में देखा कि acceleration -ve है, पर t=0 पर velocity 0 नहीं है. इसका तात्पर्य कि position vs time graph parabola के shape में होगा.

-----------------------------------------------------------------
(d)
\[ v=a+ut \]

Velocity, t=0 पर +ve है, किसी finite t पर negative हो जाती है। इसका v=u+at से मतलब की acceleration -ve है।
--------------------------------------------------------------

In Short:
(A): Uniform retardation and then uniform acceleration.
(B): Normal uniform acceleration and retardation.
(C): Uniform retardation and then uniform acceleration.
(D): Uniform retardation and then uniform acceleration.

Choose Your Frame

1. Each eyeglass frame has a series of 3 numbers imprinted. For my case it is 58/17/145.  58 (size of your glasses in millimetres)/17(the bridge width in millimetres)/145(the side length in millimetres).

2. (Source)

3.  

Vegan Food and other things to boost your mood.

FOOD:
AB
C
Cheese
Cucumber
DEFGHIJKLM
N
Nuts and seeds
O
P
Pineapples
Potato
QRS
T
Tofu
UV
W
Wheat
XYZ


OTHER THINGS:
ABCD
E
Exercise 🚲
F
G
Gut bacteria (Curd)
HIJKLMNO
P
Positivity
QR
S
Sunshine ☼
TUVWXYZ

Solution to JEE Mains 2018 Physics Q1

Q1. 1. The density of a material in the shape of a cube is determines by measuring three sides of
the cube and its mass. If the relative errors in measuring the mass and length are respectively
1.5% and 1%, the maximum error in determining the density is :
(1) 2.5%
(2) 3.5%
(3) 4.5%
(4) 6%

Ans-

\[ Density(ρ)=\frac{Mass(M)}{Volume(V)}\]
Here, the material is cube (dimension, L).
\[ ρ=\frac{M}{L^{3}}\] \[ ρ={M}{L^{-3}}\]
Maximum error in determining the density
\[ \frac{\Delta \rho }{\rho}=\frac{\Delta M }{M}+\frac{3\Delta L }{L} \]
\[ \frac{\Delta \rho }{\rho}= 1.5 + 3 × 1 \]
=4.5%
----------------------------
Combination of Errors:
1) Error of a sum or difference >
D = A + B, then maximum error in D will be ΔD = ΔA + ΔB
2) Error of a product or quotient >
a) D = AB, then the relative error in D is:
(ΔD/D) = (ΔA/A) + (ΔB/B)
b) \[D = {A^{3}}{B^{2}}{C^{-3}}\]
The relative error in D is
(ΔD/D) = 3(ΔA/A) + 2(ΔB/B) + 3 (ΔC/C) (Note: errors are always additive in nature (physics))
Why-errors-are-always-additive-in-nature-physics
----------------------------
Type in latex

Journal Publication List

Name, "title", Journal, <volume no.>, <page no.> (year)

2019
T. K. Sharma, Ravi Kumar et al., "A simple method to overcome the limitation of hybrid monochromator in the identification of peaks in the HRXRD pattern of Al0.4Ga0.6N/Al0.6Ga0.4N multi quantum wells",  Mater. Sci. Eng. B, 240, 92 (2019) DOI:10.1016/j.mseb.2019.01.010


2018

R. Kumar, V. K. Dixit, C. Mukherjee and T. K. Sharma, “Anisotropic distribution of microstructure in compressively strained InP/GaAs epitaxial layers”, Superlattices and Microstructure, 122, 636 (2018)

R. Kumar, V. K. Dixit, and T. K. Sharma, “Anisotropic distribution of dislocations density in tensile strained GaP/GaAs epilayers”, Vacuum 154, 214 (2018).

2017
S Pal , C. C. Mukherjee, V. G. Sathe , R. Kumar , P. Tiwari , V. K. Dixit , T. K. Sharma, "Self-catalyst assisted and catalyst-free epitaxial growth of InAs on Ge (111): Role of substrate surface and evolution of polytypism" J. Vac. Sci. Technol. A, 35, 06150 (2017).

2016
2015
2014
2013
2012

V K Dixit, Shailesh K Khamari, C Tyagi, S D Singh, S Porwal, R Kumar, C Mukherjee, P Mondal, A K Srivastava, T K Sharma and S M Oak "Evaluation of electronic transport properties and conduction band offsets of asymmetric InAs/InxGa1−x As/GaAs dot-in-well structures", Journal of Physics D: Applied Physics 45, 365104 (2012) DOI: 10.1088/0022-3727/45/36/365104

2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1. Ravi Kumar, V K Dixit, C Mukherjee, and T K Sharma "Anisotropic distribution of microstructure in compressively strained InP/GaAs epitaxial layers", Superlattices and Microstructures 122, 636 (2018)

2. Ravi Kumar, V K Dixit, and T K Sharma "Observation of anisotropic distribution of microstructure in GaP/GaAs epitaxial layers", Vacuum 154, 214 (2018)

4. D Singh, Ravi Kumar, T Ganguli and S S Major "High resolution x-ray diffraction study of the substrate temperature and thickness dependent microstructure of reactively sputtered epitaxial ZnO films" Mater. Res. Express 4, 096405 (2017)

5. Suparna Pal, Chandrachur Mukherjee, Vasant G Sathe, Ravi Kumar, Pragya Tiwari, Vijay Kumar Dixit, Tarun Kumar Sharma "Self-catalyst assisted and catalyst-free epitaxial growth of InAs on Ge (111): Role of substrate surface and evolution of polytypism" Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 35:  061501 (2017)

3. Ravi Kumar, V K Dixit, T Ganguli, C Mukherjee, A K Srivastava, and T K Sharma  "Observation of anisotropic distribution of microstructure in GaP/GaAs epitaxial layers", J. Appl. Phys. 120, 135307 (2016)

6. Ravi Kumar, V K Dixit, A K Sinha, T Ganguli, C Mukherjee, S M Oak, and T K Sharma "Study of the microstructure information of GaAs epilayers grown on silicon substrate using synchrotron radiation", J. synchrotron Radiat. 23(1), 238 (2016)

Dileep K. Mishra, V. G. Sathe, R. Rawat, V. Ganesan, Ravi Kumar, and T. K. Sharma "Controlling phase separation in La(5/8-y)Pr(y)Ca(3/8)MnO(3) (y=0.45) epitaxial thin films by strain disorder", Appl. Phys. Lett. 106, 072401 (2015)

Satish Kumar, Dhirendra Kumar, V. G. Sathe, Ravi Kumar, and T. K. Sharma " Absence of low temperature phase transitions and enhancement of ferroelectric transition temperature in highly strained BaTiO3 epitaxial films grown on MgO Substrates", J Appl. Phys. 117, 134103 (2015)

R.S. Ajimsha, Amit K. Das, P. Misra, M.P. Joshi, L.M. Kukreja, Ravi Kumar, T.K. Sharma, S.M. Oak " Observation of low resistivity and high mobility in Ga doped ZnO thin films grown by buffer assisted pulsed laser deposition", Journal of Alloys and Compounds 638, 55 (2015)

V K Dixit, A Marathe, G Bhatt, S K Khamari, K Rajiv, Ravi Kumar,C Mukherjee, C J Panchal, T K Sharma and S M Oak "Evaluation of structural and microscopic properties of tetragonal ZrO2 for the facet coating of 980 nm semiconductor laser diodes", J. Phys. D: Appl. Phys. 48, 105102 (2015)

Anju Ahlawat, S. Satapathy, V . G. Sathe, R. J. Choudhary, M. K. Singh, Ravi Kumar, T . K. Sharma and P . K. Gupta  "Modification in structure of La and Nd co-doped epitaxial BiFeO3 thin films probed by micro Raman spectroscopy" 46(7), 636 (2015)

Suparna Pal, S.D. Singh, V.K. Dixit, T.K. Sharma, Ravi Kumar, A.K. Sinha, V. Sathe, D.M. Phase, C. Mukherjee, Alka Ingale "Crystalline and band alignment properties of InAs/Ge (111) heterostructure", Journal of Alloys and Compounds 646, 393 (2015)

Abhishek Chatterjee, Shailesh K. Khamari, Ravi Kumar, V. K. Dixit, S. M. Oak, and T. K. Sharma "Dislocations limited electronic transport in hydride vapour phase epitaxy grown GaN templates: A word of caution for the epitaxial growers", Citation: Applied Physics Letters 106, 023509 (2015)

7. Ravi Kumar, Tapas Ganguli, Vijay Chouhan, V K Dixit, Puspen Mondal, A K Srivastava, C Mukherjee, and T K Sharma "Evaluation of Vertical Coherence Length, Twist and Microstrain of GaAs/Si Epilayers Using Modified Williamson-Hall Analysis", J Nano- Electron Phys 6, 02010 (2014)

S. D. Singh, R. S. Ajimsha, C. Mukherjee, Ravi Kumar, L. M. Kukreja, and T. Ganguli, “Realization of epitaxial ZnO layers on GaP(1 1 1) substrates by pulsed laser deposition,” J. Alloys Compd., 617, 921 (2014)

S.D. Singh, R.S. Ajimsha, C. Mukherjee, Ravi Kumar, L.M. Kukreja, Tapas Ganguli, Realization of epitaxial ZnO layers on GaP(111) substrates by pulsed laser deposition", Journal of Alloys and Compounds 617, 921 (2014) 

V. K. Dixit, Shailendra Kumar, S. D. Singh, S. K. Khamari, Ravi Kumar, Pragya Tiwari, D. M. Phase, T. K. Sharma, and S. M. Oak "Investigation of crystalline and electronic band alignment properties of GaP/Ge(111) heterostructure" Applied Physics Letters 104, 092101 (2014)

P. Mohanta, D. Singh, Ravi Kumar, Tapas Ganguli, R.S. Srinivasa, S.S. Major "Effect of ZnO buffer layer thickness on the epitaxial growth of GaN by reactive magnetron sputtering", Thin Solid Films 544, 238 (2013) 

A. Ahlawat, D. K Mishra, V. G. Sathe, Ravi Kumar and T. K. Sharma, "Raman tensor and domain structure study of single-crystal-like epitaxial films of CaCu3Ti4O12 grown by pulsed laser deposition", J. Phys.: Condens. Matter 25, 025902 (2013).

Suparna Pal, SDSingh, V K Dixit, Alka Ingale, Pragya Tiwari, Himanshu Srivastava, Ravi Kumar, C Mukharjee, P Prakash and S M Oak "Low- and high-density InAs nanowires on Si(0 0 1) and their Raman imaging" Semicond. Sci. Technol. 28,  015025 (2013)

S. D. Singh, Ravi Kumar, C. Mukherjee, P. Mondal, A. K. Srivastava, T. Ganguli, T. K. Sharma and S. M. Oak "Elastic-relaxation-induced barrier layer thickness undulations in InP/GaAs type-II quantum well superlattice structures", Semicond. Sci. Technol. 27 105031 (2012)

S. D. Singh, R. S. Ajimsha, V. Sahu, Ravi Kumar, P. Misra, D. M. Phase, S. M. Oak, L. M. Kukreja, Tapas Ganguli, and S. K. Deb "Band alignment and interfacial structure of ZnO/Ge heterojunction investigated by photoelectron spectroscopy", Appl. Phys. Lett. 101, 212109 (2012) 

V K Dixit, Shailesh K Khamari, C Tyagi, S D Singh, S Porwal, Ravi Kumar, C Mukherjee, P Mondal, A K Srivastava, T K Sharma and S M Oak "Evaluation of electronic transport properties and conduction band offsets of asymmetric InAs/InxGa1−x As/GaAs dot-in-well structures", Journal of Physics D: Applied Physics 45, 365104 (2012) 

Conference proceedings (both National and International)

Naam "title", Journal <volume no.>, <page no.> (year)

1. Ravi Kumar, V. K. Dixit, Tapas Ganguli, C. Mukherjee, A. K. Srivastava, and T. K. Sharma "Anisotropic Distribution of Dislocations Density in Tensile Strained GaP/GaAs Epilayers", International Conference on Thin Films (ICTF-2017), 13-17 November 2017, NPL, New Delhi, India.

2. Ravi Kumar, V. K. Dixit, Tapas Ganguli, C. Mukherjee, A. K. Srivastava, and T. K. Sharma "Asymmetric Dislocation Distribution and Microstructure Analysis for GaP/GaAs", International Conference on New Scintillations on Materials Horizon (ICNSMH-2016), 21-23 October 2016, M.J.P. Rohilkhand University, Bareilly (U.P.), India.

3. Ravi Kumar, Tapas Ganguli, Vijay Chouhan, and V K Dixit "The study of microstructure of III-V polar on non-polar heterostructures by HRXRD", International Symposium on Semiconductor Materials and Devices (ISSMD-2011), 28-30 January 2011, Vadodara, Gujarat, India.