At a neuron's resting potential, the inside of the axon lies about 0.07 V below the outside of the axon. Using the formula for the capacitance you found in the previous problem, how much electric energy to the nearest picojoule (1 pJ = 1x10-12 J) is stored a 8-cm-long axon at this resting potential? Make sure to include LaTeX: \kappa=7κ = 7 for the lipid bilayer. Note the capacitance may differ for different axon lengths. This electrical energy stored in the membrane due to the potential difference across the membrane is used for fast, passive transport of ions during a nerve pulse. The nerve pulse, as you'll discuss in later labs, is caused by ions rushing across the membrane, driven by this potential difference (or, equivalently, driven by the energy stored in the capacitor, just like the charge being driven through the light bulb by the capacitor in the lab).

Frost wedging occurs when water seeps into a crack in a rock, freezes, and causes the crack in the rock to widen. t or f

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.

During physical science, ms. greene challenged her students to produce an energy transformation. james and jill wrapped a 4-inch nail with a coil of fifty turns of wire. they connected one end of the coil to one terminal of a knife switch. they connected the other terminal of the knife switch to the battery. finally, they connected the end of the coil to the other terminal of the battery. james held the tip of a 1-inch nail near the flat end of the 4-inch nail. jill closed the knife switch quickly and then opened it. the 1-inch nail was pulled toward the 4-inch nail. what is the best explanation of why the nail moved? a) electrical energy was converted to mechanical energy in the 1-inch nail. b) the 4-inch nail became an electromagnet and the magnetic force attracted the 1-inch nail. c) the electric current in the 4-inch nail was converted to mechanical energy in the 1-inch nail. d) the 4-inch nail had a positive charge and the 1-inch nail had a negative charge. opposites attracted.