Recent content by Oijl

Homework Statement Derive 1/f = (n-1)*( (1/r1)-(1/r2)+(((n-1)t))/(nr1r2))) using the ray matrix method. Homework Equations Matrix for curved dielectric interface: M1 = [1, 0] [(1/r)(n1/n2 - 1), n1/n2 ] Matrix for translation through homogeneous medium: M2 = [1, d] [0...

Homework Statement Bacteria use swimming to seek out food. Imagine that the bacterium is in a region of low food concentration. For the bacterium to profit from swimming to a region with more food, it has to reach there before diffusion of food molecules makes the concentrations in the two...

Homework Statement Consider a phospholipid bilayer membrane consisting of a mixture of 90% uncharged lipid and 10% singly charged acid lipid. Assume 68 Å^2 surface area per lipid head group, and assume further that the charged lipids are uniformly distributed and immobile. The membrance is...

Homework Statement Derive z = <L>/Ltot = (2sinhßfa)/(4+2coshßfa) In the small-force limit the force-extension curve is linear, that is, in this regime the polymer behaves like an ideal Hookean spring with a stiffness constant k [is proportional to] kT/(Ltot*a). Demonstrate this claim...

Homework Statement Consider a protein sphere with a radius of 18Å, and charge Q = -10e, in an aqueous solution of c = 0.05M NaCl at 25 ˚C. We consider the small ions as point charges and use the linear approximation to the Poisson-Boltzmann equation. What is the surface potential of the...

Besides that when I solve for both A' and B' in terms of C and try to evaluate the ratio, I find (k-k1)/(k+k1) which is fine for talking about ratios, but when asked for a probability I want to give a numerical answer.

Not the right section of the forum? Sorry; where should I have posted it? The ratios are the ratios of reflected to initial, and transmitted to initial. This sounds like, then, the probability of the wave to be reflected and the probability of the wave to be transmitted. But if so, why am...

Yay, I got it! I didn't have enough faith in algebra, was my problem. I often don't. Thanks!

Homework Statement Consider particles incident (in one dimension) on a potential energy step with E>U. (That is, particles of total energy E are directed along in one dimension from a region of U=0 to a region of E>U>0.) Apply the boundary conditions for \Psi and d\Psi/dx to find the...

Homework Statement Consider particles incident on a potential energy step with E<U. (That is, a particle with total energy E travels along one dimension where U=0, then crosses, at point x=0 into a region where U>E.) (The particle is incident on the potential energy step from the negative x...

Homework Statement Consider a lamina rotating freely (no torques) about a point O of the lamina. Use Euler's equations to show that the component of \omega in the plane of the lamina has constant magnitude. [Hint: Use the reults of Problems 10.23 and 10.30. According to Problem 10.30, if...

Homework Statement In an electrom microscope we wish to study paprticles of diameter about 0.10 µm (about 1000 times the size of a single atom). What should be the de Broglie wavelength of the electrons? Through what voltage should the electrons be accelerated to have that de Broglie...

Homework Statement A triangular prism of mass M, whose two ends are equilateral triangles parallel to the xy plane with side 2a, is centered on the origin with its axis on the z axis. Find its moment of inertia for rotation about the z axis. Without doing any integrals write down and explain...

Ta-Da! Thank you, Halls of Ivy, that was kind of you. That's a load off my mind.

Homework Statement Suppose rocket traveler Amelia has a clock made on Earth. She flies to and back from a planet 12 light-years away (as measured from rest with respect to Earth) from Earth at a speed of 0.6c. Every year she sends a signal to Earth. How many signals does Earth receive by...