A laboratory technician is working with a high-speed polymer film manufacturing line. A roll of polyethylene film is rapidly unspooled over synthetic guide rollers, causing the film to accumulate a static electric charge.
Explain how the polyethylene film becomes electrically charged.
At the end of the run, the technician accidentally brings their hand near a grounded metal safety guard. A bright spark jumps across the gap. The spark lasts for a duration of 15 μs15\text{ }\mu\text{s}15 μs and 4.8 μC4.8\text{ }\mu\text{C}4.8 μC of charge is transferred.
State the equation linking charge, current, and time.
Calculate the average current in the spark. State the unit.
The metal safety guard is securely connected to the earth. Explain why the technician still experiences an electric shock when the spark discharges to this earthed guard.