Aquantum dot is modeled as a particle (exciton) of reduced mass equal to the mass of the electron confined in a cubic 3-d box of dimension l40nm on a side: (a) sketch the first four sharp energies i. e., draw an energy level diagram. label each energy with the appropriate quantum number triplet, nz; ny; n. how many different solutions to the time-independent schrödinger equation exist at each energy? (b) the confinement energy is 1.9 mev. what are the quantum numbers nai ny; n? are they uniquely determined? (c) quantum dots can be synthesised in a range of sizes, by changing the reaction conditions. if the reaction temperature is increased so that the quantum dots produced are 10% smaller in all three dimensions, how will this impact on the energy spectrum from part (a)? (d) write down a possible wavefunction for the confined particle. what is the probability density for finding the particle at position (x; y, z) = (0: 67l; 0: 67l: 0: 67l)?

Follow these directions and answer the questions. 1. set up the ripple tank as in previous investigations. 2. bend the rubber tube to form a "concave mirror" and place in the ripple tank. the water level must be below the top of the hose. 3. generate a few straight pulses with the dowel and observe the reflected waves. do the waves focus (come together) upon reflection? can you locate the place where the waves meet? 4. touch the water surface where the waves converged. what happens to the reflected wave? 5. move your finger twice that distance from the hose (2f = c of c, center of the curvature) and touch the water again. does the image (the reflected wave) appear in the same location (c of c)? you may have to experiment before you find the exact location. sometimes it is hard to visualize with the ripple tank because the waves move so quickly. likewise, it is impossible to "see" light waves because they have such small wavelengths and move at the speed of light. however, both are examples of transverse waves and behave in the same way when a parallel wave fronts hit a curved surface.

What is the scientific definition of energy that relates to work

Amass m = 74 kg slides on a frictionless track that has a drop, followed by a loop-the-loop with radius r = 18.4 m and finally a flat straight section at the same height as the center of the loop (18.4 m off the ground). since the mass would not make it around the loop if released from the height of the top of the loop (do you know why? ) it must be released above the top of the loop-the-loop height. (assume the mass never leaves the smooth track at any point on its path.) 1. what is the minimum speed the block must have at the top of the loop to make it around the loop-the-loop without leaving the track? 2. what height above the ground must the mass begin to make it around the loop-the-loop? 3. if the mass has just enough speed to make it around the loop without leaving the track, what will its speed be at the bottom of the loop? 4. if the mass has just enough speed to make it around the loop without leaving the track, what is its speed at the final flat level (18.4 m off the ground)? 5. now a spring with spring constant k = 15600 n/m is used on the final flat surface to stop the mass. how far does the spring compress?