A0.3-cm thick, 12-cm high, and 18-cm long circuit board houses 80 closely spaced logic chips on one side, each dissipating 0.04 w. the board is impregnated with copper fillings and has an effective thermal conductivity of 30 w/m˚c. all the heat generated in the chips is conducted across the circuit board and is dissipated from the back side of the board to a medium at 40˚c, with a heat transfer coefficient of 40 w/m2 ˚c. (a) determine the temperatures on the two sides of the circuit board. (b) now a 0.2-cm thick, 12-cm high, and 18-cm long aluminum plate (k = 237 w/m˚c) with 864 2-cm-long aluminum pin fins of diameter 0.25 cm is attached to the back side of the circuit board with 0.02-cm thick epoxy adhesive (k =

Scientists use laser range-finding to measure the distance to the moon with great accuracy. a brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. a laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. in order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1.0 km in diameter. staying within this diameter is accomplished by using a special large-diameter laser. part a if λ = 540nm , what is the minimum diameter of the circular opening from which the laser beam emerges? the earth-moon distance is 384,000 km. express your answer to two significant figures and include the appropriate units.

An electric clothes dryer has a resistance of 8 ohms. it draws 30 a of current. what is the voltage, in volts, of the wall outlet that it is plugged into?

A( developed during the process of technology design