JEE MAIN - Physics (2023 - 12th April Morning Shift - No. 4)

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.

Both $$\mathrm{A}$$ and $$\mathrm{R}$$ are true but $$\mathrm{R}$$ is NOT the correct explanation of $$\mathrm{A}$$
$$\mathrm{A}$$ is true but $$\mathrm{R}$$ is false
Both $$\mathrm{A}$$ and $$\mathrm{R}$$ are true and $$\mathrm{r}$$ is the correct explanation of $$\mathrm{A}$$
$$\mathrm{A}$$ is false but $$\mathrm{R}$$ is true

Explanation

Optical communication is performed in the frequency range of $1 \mathrm{THz}$ to $1000 \mathrm{THz}$. (Microwave to UV)

So, EM waves used for optical communication have shorter wavelength than that of microwaves used in RADAR.

Also, $U_{\text {INFRARED }}>U_{\text {MICROWAVE }}$

$\therefore$ Infrared EM waves are more energetic than microwave

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