Dielectric Breakdown: Videos & Practice Problems

A researcher is testing an experimental air-gap capacitor to determine its maximum charge capacity before electrical breakdown. The capacitor plates have an area of 9.2 cm² each. If the electric field strength at which dry air breaks down is 4.0 x 10⁶ V/m, determine the amount of charge that can be placed on the capacitor.

Consider a cylindrical capacitor composed of two concentric conducting cylinders with inner and outer radii, R_in and R_out. A strong, nonuniform electric field is created in the space between these cylinders, designed to ionize the air in this region. When the electric field strength exceeds the dielectric breakdown threshold of air (E_breakdown = 3.0 x 10⁶ N/C), air molecules in the region become ionized, resulting in free electrons and positively charged ions.

This ionization occurs in a specific cylindrical region around the inner conductor, extending to a radius r, which is typically five times the radius of the inner cylinder. In this setup, the inner radius of the cylinder is R_in = 0.15 mm, and the outer radius is R_out = 12.0 cm.

To generate the required electric field strength for ionization at a radius of r = 5.0 R_in, what potential difference V should be applied between the inner and outer conducting cylinders?

What is dielectric breakdown?

How does dielectric strength prevent dielectric breakdown?

During dielectric breakdown, what happens to electrons in an insulator?

What condition during a thunderstorm leads to dielectric breakdown?

Given a dielectric strength of 3×10^6 V/m, what is the minimum distance between plates to prevent breakdown at 6x10^4 V?

How does the dielectric constant affect the capacitance of a capacitor?

Using E = V/d, calculate the electric field for a capacitor with 500 V across 0.1 m plates.

Which factor decreases the risk of dielectric breakdown in a capacitor?

What principle of dielectric breakdown is illustrated by the occurrence of lightning?

Which of the following best describes dielectric breakdown?

What does dielectric strength measure in a material?

What initiates electron movement in an insulator during dielectric breakdown?

What is a key factor leading to dielectric breakdown during a thunderstorm?

For a material with dielectric strength of 4×10^6 V/m, what is the minimum plate distance for a 8x10^4 V capacitor?

Why is dielectric strength important in capacitors?

Calculate the electric field for a 600 V capacitor with plates 0.2 m apart.

How does increasing plate separation affect dielectric breakdown risk?

Why is lightning considered an example of dielectric breakdown?