Recent content by swain1

Homework Statement When an electron has tunnelled through a potential barrier it's wavefunction is described by a plane wave traveling in the positive x direction. In this region the probability density is constant. I am trying to explain why it is constant but can't find any info in books or...

Quick question Can a stationary, massive particle have a de Broglie wavelength? I thougt not but there is a question that doesn't state a speed. I think it might be incorrect. Cheers

The second one is the form given in all modern textbooks and the one you will be expected to use in your exams.

I have this formula deltav/v=3xdeltar/r Is this correct?

Ok thanks guys. I now have to work out the uncertainty in the voume of a sphere using the radius I have. Any clues on how to get the uncertainty in this value? I would expect that it would be bigger but I can't really understand why?

Homework Statement If the uncertainty in a measurement of dameter is +-0.02cm is the uncertainty in radius the same or half of this value. The formula given in wikipedia implies that it would be half of the value. Cheers Homework Equations The Attempt at a Solution

Yes it makes perfect sense but what is the type of clock called? Could a stopwatch working under this principle measure milliseconds?

Homework Statement Hi, I have been asked to research two types of clock. The first to measure periods of nanoseconds and the second, milliseconds. Obviously I have talked about atomic clocks first but what clock can measure periods of milliseconds? Cheers Homework Equations The...

Have you read anything on QED. A good qualititave explanation can be found in Feynman's book of he same name. I think that would answer all of your questions.

yes the energy transfer will be the same but not the entropy.??

Homework Statement Calculate the changes in total entropy of the universe as a result of the following processes: (a) A block of mass 6kg and heat capacity of 300 J/K/kg at 150oC is placed in a lake at 0oC. Homework Equations The Attempt at a Solution I think I have found the entropy change...

The thing I consider confusing in this thread is the way frequency is being thought of. It simply is a number of an event in an amount of time. In this case we are talking about waves. Therefore, the number of oscillations per unit time, be it light waves or mechanical waves the same principals...

Yes it was, that is what I thought it would be but then I was wondering why the potential could be zero inside the well as this is meant to represent a bound particle. Also for a completely free particle, would there be a restriction on the value of n? cheers

I am just trying to get my head round how this models the electron bound to an atom. I don't understand why the potential is zero in the well What physical case corresponds to the condition that V(x)=0 for all values of x? Thanks

I have moved the equation now. If you look at the question you will see that 7000 has units of watts. Is it wrong anyway?