Which of the following best describes a detonator?

A detonator is best described as a device containing a small detonating charge for explosives. Its primary function is to initiate the explosion of a larger quantity of explosive material. Detonators can be electric or non-electric and are crucial in various applications, including mining, construction, and demolition. They work by providing a controlled means to trigger an explosive reaction, enabling safe and effective use of explosives in various operations.

While other options may describe related tools or devices, they do not accurately capture the essential purpose and characteristics of a detonator. For instance, a device designed only for electric circuits would be limited in its function and scope, excluding the important non-electric types of detonators. A measuring instrument for charge weight does not pertain to initiation but rather to the measurement process, which is distinct from the detonator's function. Lastly, a device for safely extracting coal pertains to mining equipment but is unrelated to the explosive initiation process that a detonator facilitates. Understanding these distinctions highlights the critical role of detonators in managing and executing explosive tasks safely and effectively.