How can the magnetic field be seen around a wire?

a. using a battery
b. with an insulator
c. using iron filings
d. it is always visible

Agas contained within a piston-cylinder assembly undergoes three processes in series: process 12: compression with pv= constant from 1 bar and 1 liter to 4 bar. process 23: constant pressure expansion to 1 liter. process 31: constant volume calculate the pressure and volume at each state, and sketch the processes on a p-vdiagram labeled with pressure and volume values at each numbered stat

Which sound characteristic is not affected by the relative motion of an object

What is the equation for electrical work?