Earliest practical applications of electromagnetic waves Historically, what were among the earliest widespread uses of electromagnetic waves?

Introduction / Context:
Understanding the chronology of electromagnetic (EM) technology helps frame how modern wireless systems evolved. The earliest practical deployments focused on sending information over distance without wires, long before the advent of sophisticated detection systems such as radar.

Given Data / Assumptions:

• Late 19th to early 20th-century developments.
• Key figures: Hertz (experiments), Marconi (wireless telegraphy).
• Focus on “earliest uses” in real systems.

Concept / Approach:
Heinrich Hertz demonstrated EM wave propagation in the 1880s. Soon after, Guglielmo Marconi pioneered wireless telegraphy for point-to-point communication across increasing distances, culminating in transatlantic messages by the early 1900s. These point-to-point links—ships to shore, coastal stations, military—constituted the earliest large-scale use of radio waves. Radar, by contrast, emerged later (1930s–1940s), driven by the need for object detection and ranging, especially around World War II. Thus, communication predates radar as the earlier widespread application.

Step-by-Step Solution:

Verification / Alternative check:
Historical timelines in communications engineering show wireless telegraphy and telephony deployments well before large-scale radar systems, confirming the ordering.

Why Other Options Are Wrong:

• Radar: important but later in chronology.
• Both (a) and (b): overstates; only (a) qualifies as earliest widespread use.
• Neither: ignores the foundational role of early radio links.

Common Pitfalls:
Associating early experiments with practical deployment; confusing timelines influenced by wartime acceleration of radar development.

Final Answer:
point to point communication