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. Guglielmo Marconi
B. Nikola Tesla
C. Heinrich Hertz
D. Thomas Edison
Answer: Option C
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:
Dimensionless quantities: angle (radian = arc/radius), strain (ΔL/L), refractive index (ratio of speeds). All have [M⁰L⁰T⁰]. Memory aid: 'Ratios of same dimensions ⇒ dimensionless'. Dimensional analysis question frequently tested in competitive exams to identify dimensionless physical quantities.
Explanation:
For resistors in parallel, the reciprocal of the equivalent resistance (1/Rp) is the sum of the reciprocals of individual resistances. 1/Rp = 1/R1 + 1/R2 + 1/R3 = 1/2 + 1/3 + 1/6. Finding a common denominator (6): 1/Rp = 3/6 + 2/6 + 1/6 = 6/6 = 1. Therefore, Rp = 1 Ω.
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