The digital payment system that enables sellers to accept payment at trade shows, food trucks, concerts, or farm stalls is called a:
A. biometric authentication system.
O B. QR code.
O c. payment protection device.
D. mobile point-of-sale device.
SUBMIT

Asquare isothermal chip is of width w=5 mm on a side and is mounted in a substrate such that its side and back surfaces are well insulated; the front surface is exposed to the flow of a coolant at tinf=15 °c. from reliability considerations, the chip temperature must not exceed t=85 °c. if the coolant is air and the corresponding convection coefficient is h=200 w/m2 x k, what is the maximum allowable "power" of the chip? if the coolant is a liquid for which h=3000 w/m2 x k, what is the maximum allowable power of the chip?