Who among the following scientists first experimentally demonstrated the existence of electromagnetic waves, confirming Maxwell's theoretical predictions? MCQ with Answer and Explanation
Who among the following scientists first experimentally demonstrated the existence of electromagnetic waves, confirming Maxwell's theoretical predictions?
A. Nikola Tesla
B. Heinrich Hertz
C. Guglielmo Marconi
D. Thomas Edison
Answer: Option B
Solution (By JKSSB Mock Tests)
While James Clerk Maxwell predicted electromagnetic waves mathematically, it was the German physicist Heinrich Hertz who successfully built the first spark-gap transmitter in 1887. He physically generated and detected radio waves in his laboratory, proving Maxwell's theories right. The SI unit of frequency, the Hertz (Hz), is named in his absolute honor.
Explanation:
Power = work/time = 500/10 = 50 W. Watt = Joule/second. This is average power. Simple division. Higher power means faster rate of doing work.
Explanation:
Spectrometer measures wavelengths of light using diffraction gratings or prisms to disperse light and angular measurements. Interferometer (D) can also measure wavelength but spectrometer is the standard instrument for spectral analysis. Microscope and telescope magnify images, not measure wavelength. Memory tip: 'Spectrometer = wavelength measurement via dispersion; used in spectroscopy'. This instrument-application question tests practical physics knowledge, frequently examined in competitive exams. Always associate instruments with their primary function; competitive exams often test context-specific uses.
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