I am an A Level Physics students and I have tonnes of questions to ask. So, below are some of them. Hope you will answer them. Please answer the ones you have any idea about even if just a singe question. Hope I will get the answers! The only difference between Kelvin and Celsius is the y-intercept(Since T = θ + 273). Then, how simply using Kelvin instead of Celsius fix the problem of different types of thermometer disagreeing with each other even at the same temperature.(The reason my teacher gave for why do they disagree was, because the property whose change we measure does not vary linearly(and in different ways in different thermometers) with temperature but after determining the fixed points, we assume that they vary like that.) So, if the reason my teacher gave me is correct, what difference would the use of Celsius or Kelvin make on that?(Hope you got what I meant!) Will a matter have zero internal energy at zero Kelvin(let's assume that it can be attained)? My answer is no because internal energy is not only the energy due to the temperature(kinetic energy). Internal energy is the sum of the kinetic and potential energy. So, at zero Kelvin, though the kinetic energy is zero, potential energy isn't. So, the internal energy must not be zero! Am I correct? Why does specific heat capacity vary from one material to the other and why does it depend on the temperature? Dulong and Petit's law states that "all solids have nearly 25 Jmol-1Kmol-1 specific heat capacity." This implies that specific capacity depends on the number of atoms or molecules. But, number of atoms/molecules per unit volume is closely related to density. So, does that mean that specific capacity of a substance depends on the density of the substance? Further, the number of atoms/molecules depends on the mass as n = (M/Mr). That implies a relation between specific heat capacity and mass but there is none. Please explain. Why do moving charge particles get affected by magnetic filed? Because they themselves have a magnetic field, right? Then, how does a moving charge generate magnetic field? Any body follows Simple Harmonic Motion if a [itex]\alpha[/itex] -x. Well, in a recent exam, we had a question in which there was a sinusoidal graph given and the question that was asked underneath was something like, "What feature of the above graph tells you that the object is following Simple Harmonic Motion?" I wrote "sinusoidal nature of the graph" and scored zero. My teacher reported that the answer is, "constant time period" But, I believe that, Simple Harmonic Motion implies constant time period but the converse is not always true. From the equilibrium position, I can have a body move super-fast to a certain point(before the extreme end), then stop for a while and then slowly move to the extreme end and then return back to the equilibrium in another unpredictable way. We can have all that and still have a constant time period but that won't be a simple harmonic motion, will it? And, shouldn't "sinusoidal nature of the graph" be the correct answer because the solution of the differential equation d2x/dt2 = -kx will be a sine function(or cosine)? And, the last but not the least, can someone give me a good link to study operational amplifier. All the books I have start with too technical touch and I want someone gentle and something like written for a layman. Can I find something like that? It would be a great relief if I did. Hope you understood my questions and hope someone out there will help! And, sorry for my not so good English!