Suppose that two plates of indefinite thickness, initially at different temperatures, are brought into contact at t = 0. plate 1, with thermal properties a 1 and kb is at x < 0 and has initial temperature t1; plate 2, with properties a 2 and k2, is at x > 0 and has initial temperature t2. determine the temperatures in both plates, expressed as @ = (t- t2)j(t1 - t2). is the temperature at x = 0 constant or does it vary with time? (hint: it will be to use similarity variables of the form tji = xj[2(ait) 112 ] .)

Antireflective coatings on solar cells are often made by applying a thin film of silicon nitride (sinx), which has an index of refractive of 1.2, on the top of the silicon solar cell, which has a refractive index of about 3.5. however, the sun emits radiation of various wavelengths which the solar cell absorbs, and the antireflective coating can only absolutely minimize the reflection of one of these wavelengths. the coating thickness is chosen to reduce the reflection of green/yellow light (e = 2.2 ev), which is the most intense color in the solar spectrum (shown below). which of the following coatings would minimize reflection of green/yellow light? the answer is 820 nm how? what is the angular width of the central maximum of an electron traveling at 2 x 108 m/s going through a single slit of width 1 mm.