Which statement describes the SI unit of the electric field?

Which statement describes the SI unit of the electric field?

• A. Tesla.
• B. Ampere.
• C. Coulomb.
• D. Volts per meter.

Answer: (D)

Electric field strength is defined as the force acting on a positive test charge per unit charge, so its unit must combine force and charge. That gives Newtons per Coulomb. Since 1 volt per meter is mathematically equivalent to 1 newton per coulomb (1 V/m = 1 N/C, because V = J/C and J = N·m, so V/m = (N·m/C)/m = N/C), the SI unit commonly used for the electric field is volts per meter. The other options correspond to magnetic field (Tesla), electric current (Ampere), and electric charge (Coulomb), not the field strength. For example, a field of 1 V/m means a 1 N force would act on a 1 C charge.

Electric field strength is defined as the force acting on a positive test charge per unit charge, so its unit must combine force and charge. That gives Newtons per Coulomb. Since 1 volt per meter is mathematically equivalent to 1 newton per coulomb (1 V/m = 1 N/C, because V = J/C and J = N·m, so V/m = (N·m/C)/m = N/C), the SI unit commonly used for the electric field is volts per meter. The other options correspond to magnetic field (Tesla), electric current (Ampere), and electric charge (Coulomb), not the field strength. For example, a field of 1 V/m means a 1 N force would act on a 1 C charge.