What is the term for an electric field of constant strength where the field lines are parallel and equally spaced?

The term that describes an electric field of constant strength, where the field lines are parallel and equally spaced, is a uniform electric field. In a uniform electric field, the force experienced by a charged particle is the same regardless of its position within the field. This consistency is illustrated by the parallel and evenly spaced field lines, indicating that the strength of the electric field does not change with distance.

In contrast, other types of electric fields may exhibit variations in strength. For instance, a static electric field refers to an electric field that does not change with time, without necessarily being uniform. A dynamic electric field varies over time, often associated with changing magnetic fields. A variable electric field indicates a field whose strength changes with position, which is different from the uniform field characteristics. Therefore, the clear definition and characteristics of a uniform electric field affirm that it is the correct answer to the question.