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Nischal Singh Dangol Asked:
How to get A in physics?
Whatever the syllabus or course, an A grade means “Excellent work indicating a clear mastery of the subject material”
This requires evidently a basic understanding of the subject, thorough with the fundamentals and the ability to apply the principles to solve problems creatively. One should be able to make suitable connections between concepts logically to solve the problem in hand. (Remember, Physics is often referred to as a Problem Solving Discipline)
A grade in Physics comes naturally if you start loving the subject and take active interest in applying the concepts of Physics to solve problems (in subject as well as in day to day life situations)
Also important :
- Maintaining good rapport is also important in getting an A grade.
- Attend all lectures/classes and never bunk
- Do your assignments sincerely and submit in time
Wish you all the best.
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Use the commenting system to post your ideas.
In the model of the big bang I would like to pose the following question. My understanding is that
1. The expansion of the universe is accelerating and
2. The radiation or shock wave to keep the analogy going is something we can measure.
My question is this. While we can rewind the clock to a single moment when the universe was infinity dense how do we know that this was a moment at all. Let me elaborate. As the universe expands could time or space time not also expand and if so than when the big bang occurred is something we cannot measure merely by rewinding the clock. If we are experiencing time at a given rate when the universe is at its current size would time not be being effected by the expansion also and if so would that mean the there was simply no start and no end to the universe? Perhaps the big bang is not as accurate as we may wish and perhaps it is our ability to comprehend that is limited. I propose there is no start or end to the universe it has always and will always be as it, and we, cannot exist without time and as such these two objects or things form a symbiotic relationship with each other. While the universe expands so does time and its effects are reduced in line with its expansion. Does this sound plausible and if not why?
“Please explain electric potential in some other
words, other than every book,every author says..I
want something different..”
If you know the meaning of the word POTENTIAL, and already studied gravitational potential, then understanding Electric Potential would be quite easy.
We know the law of conservation of energy which states that “Energy can neither be created nor be destroyed; it can be transformed from one form to another or be transferred from one body to another”
If we imagine a positive point charge kept at a point, and if we want to bring another positive point charge closer to it, we have to perform some work. This work done is stored as the potential energy of the system. The work done in doing so depends on (i) the magnitude of the original charge and (ii) the distance at which the new charge is brought.
The Electric Potential at a point in an Electric Field is a measure of the work required to bring a unit positive charge taken from infinity to the point against the electrostatic force and brought without any acceleration.
Please refer to the following links for detailed information
Understanding the unnaturally small size of the cosmological constant poses one of severest challenges for a theory of gravity. At late times and for large distances, the apparent size of the cosmological constant is constrained to be extremely small in terms of the natural scale for gravity, the Planck mass. In contrast, no observations bound the value of the cosmological constant during the earliest stages of the universe, when corrections to the Einstein-Hilbert action were non-negligible, and its presence can lead to a richer family
of metrics. Among the solutions for a more general gravitational action, the presence of a positive cosmological constant does not inevitably lead to a de Sitter expansion. Such solutions must still yield or evolve into a low energy theory in which the effective cosmological constant is small to be phenomenologically acceptable. If the characteristic scales on which these metrics vary are of extremely high energy or short distance, then it may be possible to integrate out such features to arrive at a slowly varying e®ective theory.
To determine whether an action for gravity, generalized beyond an Einstein-Hilbert term, admits these features | natural coefficients for the terms in the action and a rapid variation | we must ¯rst solve the highly non-linear field equations. This task is difficult even when only the next curvature corrections are added. In 3 + 1 dimensions, Horowitzand Wald and later Starobinsky  discovered oscillating solutions for actions that
included quadratic curvature terms but no cosmological constant. Numerical solutions were found in 4 + 1 dimensions in the presence of a cosmological constant and a scalar field, along with the quadratic curvature terms. In this latter scenario, metrics exist that depend periodically on the extra spatial coordinate so that choosing the size of the extra dimension to be the period produces a compact extra dimension without any fine-tunings or singularities. The parameters in the action ¯x the size of the extra dimension uniquely.
However, without an analytical approach it becomes di±cult to generalize these solutions to include an evolution in time. Without this freedom, it is di±cult to understand how a universe starting from a more general state can find itself in one of these configurations.