Dielectric strength of pure air at normal temperature and pressure is:

Explanation:

Dielectric Strength of Air

Definition: Dielectric strength refers to the maximum electric field that a material can withstand without experiencing electrical breakdown. For air, this is the maximum voltage per unit distance that air can handle before it becomes conductive, leading to a breakdown and allowing current to flow through it.

Dielectric Strength of Air: The dielectric strength of pure air at normal temperature and pressure is approximately 30 kV/cm (kilovolts per centimeter). This means that air can withstand an electric field of up to 30,000 volts per centimeter before it breaks down and becomes conductive.

Explanation of Correct Option:

Given the options:

• Option 1: 30 V/cm
• Option 2: 30,000 V/cm
• Option 3: 30,000 V/m
• Option 4: 3,000 V/cm

The correct answer is Option 2: 30,000 V/cm. This option correctly represents the dielectric strength of air under standard conditions. The dielectric strength of air is typically around 30 kV/cm, which translates to 30,000 V/cm. This value indicates the maximum electric field that air can withstand before it breaks down and allows electrical discharge.

Additional Information

To further understand the analysis, let’s evaluate the other options:

Option 1: 30 V/cm

This option is incorrect as it significantly underestimates the dielectric strength of air. Dielectric strength values for air are much higher than 30 V/cm, typically around 30,000 V/cm.

Option 3: 30,000 V/m

This option is incorrect as it represents the dielectric strength in volts per meter (V/m) rather than volts per centimeter (V/cm). Converting 30,000 V/m to V/cm results in 300 V/cm, which is still not the correct value for the dielectric strength of air.

Option 4: 3,000 V/cm

This option is incorrect as it underestimates the dielectric strength of air. The correct value is approximately 30,000 V/cm, not 3,000 V/cm.

Conclusion:

Understanding the dielectric strength of air is crucial for various applications, including the design of electrical insulators and the safety measures in high-voltage equipment. The dielectric strength of pure air at normal temperature and pressure is approximately 30,000 V/cm, which is significantly higher than the values provided in the incorrect options. This value indicates the maximum electric field that air can withstand without breaking down and becoming conductive, ensuring proper insulation and preventing electrical discharges in electrical systems.