Electric Field Calculator
Calculate electric field from force and test charge.
Formula
E = F/q.
What Is Electric Field Strength?
Electric field strength describes the force experienced per unit positive test charge at a point in an electric field. It is measured in newtons per coulomb (N/C), which is equivalent to volts per meter (V/m).
Example Calculation
If a test charge of 0.002 C experiences a force of 6 N, the field strength is E = 6 / 0.002 = 3,000 N/C.
Factors and Interpretation
For a fixed force, a smaller test charge produces a larger calculated force-per-charge ratio. In practice, the test charge should be small enough that it does not significantly disturb the original field. Direction is defined as the direction a positive test charge would accelerate.
Frequently Asked Questions
Are N/C and V/m equivalent?
Yes. Both units describe electric field strength.
Can electric field be negative?
The field is a vector. A negative component indicates direction relative to the chosen axis; this calculator reports the signed ratio from the entered values.
Does the test charge create the field?
No. It is used to measure or define the field produced by other charges or sources.
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Formula and Practical Limits
Electric field strength from a point charge follows E = kQ/r² in the ideal model. Multiple charges require vector superposition, and conductors or dielectric materials can alter the field distribution.