Question

According to the definition of the ampere, the constant current maintained in each of two infinitely long, straight, parallel conductors of negligible circular cross-section, placed 1 metre apart in a vacuum, produces a force between them equal to:

Options

• 3 × 10⁻⁵ N per metre of length

• 2 × 10⁻⁵ N per metre of length

• 2 × 10⁻⁷ N per metre of length

• 4π × 10⁻⁷ N per metre of length

Answer 1

The ampere is defined as the constant current which, when maintained in each of two infinitely long, straight, parallel conductors of negligible circular cross-section, placed 1 metre apart in a vacuum, produces a force of 2 × 10⁻⁷ N per metre of length between them.