Sir Isaac Newton: Identify the key device he himself invented. Full question: What did Sir Isaac Newton invent? Choose the correct option.

Given data

• Topic: An invention attributable to Sir Isaac Newton.

Concept / Approach
Beyond his laws of motion and gravity, Newton built the first practical reflecting telescope, now known as the Newtonian telescope, using a concave mirror to eliminate chromatic aberration common in refracting telescopes.

Option analysis
Reflecting telescope: Correct. Microscope: Advanced by Hooke and Leeuwenhoek. Lightning rod: Benjamin Franklin. Internal combustion engine: 19th–20th century development, not Newton.

Final Answer
Reflecting telescope (Newtonian telescope).