Question

The electrical breakdown of an insulator occurs when an electric field becomes large enough to ionize the insulator, allowing electrical current to flow; lightning is an example of the electrical breakdown of air. The electrical breakdown of air occurs when the electric field reaches about 3×106 N/C . Estimate the magnitude of the total static charge on your body ?body when you generate a static spark with your fingertip when getting out of your car. Assume a spark gap of 1 mm .

> Feedback Assume that the static charge on your fingertip is primarily responsible for the electric field you generate near the door right before you touch it. Treat the charge on your fingertip as a point charge. The magnitude of the electric field generated by a point charge is proportional to the magnitude of charge and inversely proportional to the square of the distance away from the charge. Additionally, assume a uniform static charge density over the surface of your body. A uniform surface charge density ơ is calculated by dividing the total charge on the surface Q by the area of the surface A. Estimate the percentage that the surface area of one fingertip contributes to your overall body surface area Combine all this information to estimate the total static charge on your body.

Answer 1

The static charge generate an equal and opposite charge on the door of the car. So, whole system of the and door will act as a capacitor. The capacitance is, delta V = Ed (3 times 10^6 N/C)(1mm) (1m/10^3mm) 3 times 10^3 V The magnitude of the total static charge is, Q = E/delta V Q = 3 times 10^6 N/C/3 times 10^3 V Q = 10^3C