After walking across a carpet, a boy feels a spark between his hand and a doorknob.

if the boy's hand is negatively charged just before he touches the doorknob, which particles moved from the carpet to his hand (chose one of the answers below)

a atoms
b electrons
c neutrons
d protons

Consider the growth of a 20-nm-diameter silicon nanowire onto a silicon wafer. the temperature of the wafer surface is maintained at 2400 k. assume the thermal conductivity of the silicon nanowire is 20 wm-1k-1 and all its surfaces including the tip are subjected to convection heat transfer with the coefficient h = 1×105 wm-2k-1 and t∞ = 8000 k. when the nanowire grows to l = 300 nm, what is the temperature of the nanowire tip (t (x =