Given below are two statements: one is labelled as Assertion A and… | JEE Main 2023 (12 Apr, Shift 1)

Q10JEE Main 2023 · 12 APR · SHIFT 1Medium

Electromagnetic Spectrum & Atmosphere

Given below are two statements: one is labelled as Assertion $\mathbf{A}$ and the other is labelled as Reason $\mathbf{R}$

Assertion A: EM waves used for optical communication have longer wavelengths than that of microwave, employed in Radar technology.

Reason R: Infrared EM waves are more energetic than microwaves, (used in Radar) In the light of given statements, choose the correct answer from the options given below.

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Answer: (d)

Optical communication uses infrared/visible light ( $\lambda \sim 1\ \mu\text{m}$ ); radar uses microwaves ( $\lambda \sim \text{cm}$ ).
So optical waves have shorter wavelength than radar microwaves: A is false.
$E = h\nu$ and infrared has higher $\nu$ than microwaves, so infrared photons are more energetic: R is true.
So the answer is (d) A is false but R is true.

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Electromagnetic Spectrum & Atmosphere question from JEE Main 2023 (12 Apr, Shift 1)

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