物理
已验证计算器，公式透明
Current Density Calculator.
Calculates current density from electric current and cross-sectional area, or derives current or area when the other two are known.
您的输入
工作原理
- 1
Enter the electric current in amperes.
- 2
Enter the cross-sectional area in square millimeters.
- 3
The calculator divides current by area (converted to square meters) to get current density in A/m².
- 4
Review the secondary result in A/mm² for convenience.
current / (area / 1e6)常见问题
What is current density?
Current density is the amount of electric current flowing through a unit cross-sectional area. It is measured in amperes per square meter (A/m²).
Why use mm² for area?
In electrical engineering, wire cross-sections are commonly given in mm². The calculator converts to m² automatically for the standard unit.
Can I use this for any conductor?
Yes, as long as the current is uniformly distributed across the cross-section. For non-uniform distributions, local current density varies.
工作原理
Calculates current density from electric current and cross-sectional area, or derives current or area when the other two are known.
- Enter the electric current in amperes.
- Enter the cross-sectional area in square millimeters.
- The calculator divides current by area (converted to square meters) to get current density in A/m².
- Review the secondary result in A/mm² for convenience.
公式
此计算器背后的数学公式，供您核对结果。
Current Density
Current density (J) equals the current (I) divided by the cross-sectional area (A).
Example:
Input: I = 5 A, A = 2.5 mm²
Calculation: 5 / (2.5 × 10⁻⁶) = 2,000,000 A/m²
Result: 2,000,000 A/m²
实际应用场景
此计算在日常生活中的应用。
Wire sizing
Determine if a wire can safely carry a given current without overheating.
Example: Check if 2.5 mm² wire handles 20 A.
PCB trace design
Ensure copper traces have adequate cross-section for the current they carry.
Example: Calculate current density for a 1 oz copper trace.
Electrochemistry
Evaluate electrode performance in electrolysis or batteries.
Example: Find current density on an electrode surface.
提示与常见错误
Tips
- Use consistent units: current in amperes, area in mm².
- For round wires, area = π × (diameter/2)².
- Typical safe current densities for copper are around 4-10 A/mm².
- Higher current density increases heating and voltage drop.
Common Mistakes to Avoid
- Forgetting to convert mm² to m² when using standard units.
- Using diameter instead of radius in area calculations.
- Assuming uniform current density when it may not be.
假设与限制
- Use the stated inputs and units.
- Results are estimates for planning and education.
- Check measurements and source data before making an important decision.