1
JEE Main 2023 (Online) 12th April Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

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.

A
Both $$\mathrm{A}$$ and $$\mathrm{R}$$ are true but $$\mathrm{R}$$ is NOT the correct explanation of $$\mathrm{A}$$
B
$$\mathrm{A}$$ is true but $$\mathrm{R}$$ is false
C
Both $$\mathrm{A}$$ and $$\mathrm{R}$$ are true and $$\mathrm{r}$$ is the correct explanation of $$\mathrm{A}$$
D
$$\mathrm{A}$$ is false but $$\mathrm{R}$$ is true
2
JEE Main 2023 (Online) 11th April Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

A plane electromagnetic wave of frequency $$20 ~\mathrm{MHz}$$ propagates in free space along $$\mathrm{x}$$-direction. At a particular space and time, $$\overrightarrow{\mathrm{E}}=6.6 \hat{j} \mathrm{~V} / \mathrm{m}$$. What is $$\overrightarrow{\mathrm{B}}$$ at this point?

A
$$-2.2 \times 10^{-8} \hat{i} T$$
B
$$2.2 \times 10^{-8} \hat{i} T$$
C
$$2.2 \times 10^{-8} \hat{k} T$$
D
$$-2.2 \times 10^{-8} \hat{k} T$$
3
JEE Main 2023 (Online) 11th April Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The electric field in an electromagnetic wave is given as

$$\overrightarrow{\mathrm{E}}=20 \sin \omega\left(\mathrm{t}-\frac{x}{\mathrm{c}}\right) \overrightarrow{\mathrm{j}} \mathrm{NC}^{-1}$$

where $$\omega$$ and $$c$$ are angular frequency and velocity of electromagnetic wave respectively. The energy contained in a volume of $$5 \times 10^{-4} \mathrm{~m}^{3}$$ will be

(Given $$\varepsilon_{0}=8.85 \times 10^{-12} \mathrm{C}^{2} / \mathrm{Nm}^{2}$$ )

A

$$17 \cdot 7 \times 10^{-13} \mathrm{~J}$$

B
$$28 \cdot 5 \times 10^{-13} \mathrm{~J}$$
C
$$8 \cdot 85 \times 10^{-13} \mathrm{~J}$$
D
$$88 \cdot 5 \times 10^{-13} \mathrm{~J}$$
4
JEE Main 2023 (Online) 10th April Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The amplitude of magnetic field in an electromagnetic wave propagating along y-axis is $$6.0 \times 10^{-7} \mathrm{~T}$$. The maximum value of electric field in the electromagnetic wave is

A
$$6.0 \times 10^{-7} ~\mathrm{Vm}^{-1}$$
B
$$5 \times 10^{14} ~\mathrm{Vm}^{-1}$$
C
$$180 ~\mathrm{Vm}^{-1}$$
D
$$2 \times 10^{15} ~\mathrm{Vm}^{-1}$$
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