Two very large, nonconducting plastic sheets, each 10.0 cm thick, carry uniform charge densities σ1,σ2,σ3 and σ4 on their surfaces, as shown in the following figure(Figure 1). These surface charge densities have the values σ1 = -7.40 μC/m2 , σ2=5.00μC/m2, σ3 = 1.20 μC/m2 , and σ4=4.00μC/m2. Use Gauss's law to find the magnitude and direction of the electric field at the following points, far from the edges of these sheets.

need to see circuit to get time constant

iron would move it is magnetic there is a mag field around the current in the wire

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me