Recent content by andyfreesty1e

Homework Statement The 4p → 4s transition in 19K produces a pair of lines at 766.49nm and 769.90nm. Estimate the value of <(1/r)dV/dr> for the optically active electron in 19 K Homework Equations The Attempt at a Solution help needed urgently please. All i know so far is...

Homework Statement The universe is expanding as shown by a Hubble constant H of 75 Km s^-1 Mpc^-1, but a constant density of matter of 10^-26 kg m^-3 is maintained by the continuous creation of hydrogen atoms as the universe expands. Find the rate of creation of hydrogen atoms per unit...

Homework Statement calculate the correction to the energy of the ground state of the hydrogen atom due to the finite size of the nucleus treating the nuclear charge as a thin shell of radius r0. I posted this not that long ago, i know what to do but i just can't figure out what the...

Homework Statement Find an expression for the correction to the energy of the ground state of the hydrogen atom due to the finite size of the nucleus. Treat the nuclear charge as a thin shell of radius r0. what i have been thinking is that you the size of the nucleus as a perturbation, but...

sorry to keep asking questions, i think I am being a bit stupid, just to clarify something, in my above post would Psi(x,0) be my initial wavefunction, the one where the potential has not changed, and psi* would be the wavefunction when the potential has changed? thanks

so the ground state before is (1/a(sqrt Pi))^1/2 exp[-x^2/2a^2] where a=(h_bar/mw)^1/2 and w=(k/m)^1/2 so the ground state after is the same but w=(a^4k/m)^1/2 ? so then calculate c=integral (psi*Psi(x,0))dx and then c^2 is the probability? does this seem about right?

Quantum Physics Help! Homework Statement The spring constant for a particle in the ground state of a simple harmonic oscillator changes by a factor a^4 instantaneously, what is the probability that the particle is observed in the ground state of the new potential immediately following the...

urgent electromagnetism help Homework Statement Assume that dust particle in the solar system are spherical, black and have a density of 2000kg/m^3. Use the total luminosity of the sun to calculate the time average poynting vector of the radiation at a distance r from the Sun. Hence...

Homework Statement Evaluate the divergence and curl of the following vectors. A(r) is everywhere parallel to the y-axis with a magnitude A = cx + A0 , where c and A0 are constants. Homework Equations The Attempt at a Solution I can evaluate the div and curl, but i don't know...

Ok, so according to my textbook, i would use cylindrical gaussian surface. It tells me how to find the electric field, but i can't see how to work out the electric field vector.

i still don't really know where to go with it, any other hints you can give?

Homework Statement Use Gauss’s law to obtain a vector expression for the electric field produced by an infinte sheet of charge with a surface density of 1 C m−2 , confined to the xy plane. Hence show that the divergence of this electric field is zero for all points not in the xy plane...