Radar, a system for detecting distant objects using radio waves, was pioneered and invented in practical form by which scientist?

Introduction / Context:
Radar, short for radio detection and ranging, became crucial for navigation and military defence in the twentieth century. Many physicists contributed to the underlying science of radio waves, but general knowledge questions usually ask for the person credited with developing the first practical radar system, Robert Watson Watt. This question checks whether the learner can distinguish between early radio experimenters and the engineer who turned the concept into an operational technology.

Given Data / Assumptions:
• The subject is radar as a practical system used to detect aircraft and other distant objects.
• Options include Robert Watson Watt, Guglielmo Marconi, Heinrich Hertz, and Thomas Alva Edison.
• The question expects you to know which scientist is most often associated with the invention of radar in a practical sense, not just with general radio work.

Concept / Approach:
The approach is to separate the discovery of radio waves from the engineering of radar. Heinrich Hertz experimentally confirmed electromagnetic waves, Guglielmo Marconi built radio communication systems, and Thomas Edison worked on many electrical devices. Robert Watson Watt, however, directed work in Britain that led to the first operational radar network before the Second World War. Therefore, he is commonly named as the inventor of practical radar in exam material.

Step-by-Step Solution:
Step 1: Focus on radar as a system that sends out radio waves and detects reflected signals to locate objects.
Step 2: Recall that Robert Watson Watt led a team in the United Kingdom that developed early warning radar stations which played a key role in wartime defence.
Step 3: Recognise that Heinrich Hertz demonstrated the existence of electromagnetic waves but did not build radar systems.
Step 4: Remember that Guglielmo Marconi concentrated on long distance radio communication and wireless telegraphy.
Step 5: Note that Thomas Alva Edison invented many electrical devices such as light bulbs and phonographs but is not linked to radar.

Verification / Alternative check:
To verify, think of standard history of radar accounts, which usually highlight Watson Watt and his role in establishing the British early warning chain of radar stations. While other scientists laid the groundwork, exam oriented texts often treat Watson Watt as the radar inventor. Because the question speaks of invention in a straightforward way, and not of basic theory of waves, this matches the practical achievement of Watson Watt rather than the contributions of Hertz or Marconi.

Why Other Options Are Wrong:
Guglielmo Marconi is wrong because his primary achievement was wireless telegraphy and radio communication. Heinrich Hertz is wrong because he confirmed electromagnetic waves but did not implement radar systems. Thomas Alva Edison, although a very famous inventor, worked mainly on electric lighting, sound recording, and related devices. None of these match the specific practical development of radar technology in defence applications.

Common Pitfalls:
Some learners may select Heinrich Hertz or Guglielmo Marconi because they strongly associate these names with radio. However, the key idea is that radar is a set of equipment that uses radio waves for detection, not just the discovery of radio waves themselves. By remembering the phrase Watson Watt and radar chain of stations, you can anchor this knowledge and avoid confusion in multiple choice questions that mix several radio pioneers together.

Final Answer:
The scientist most widely credited with developing practical radar is Robert Watson Watt.