Why do we use deciBels instead of microbars to relate to sound pressure level?

Steel is coated with a thin layer of ceramic to protect against corrosion. what do you expect to happen to the coating when the temperature of the steel is increased significantly? explain.

Slip occurs via two partial dislocations because of (a) the shorter path of the partial dislocation lines; (b) the lower energy state through partial dislocations; (c) the charge balance.

The higher the astm grain size number, the finer the gran is. a)-true b)-false