1
JEE Main 2021 (Online) 16th March Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
A plane electromagnetic wave of frequency 500 MHz is travelling in vacuum along y-direction. At a particular point in space and time,
$$\overrightarrow B $$ = 8.0 $$\times$$ 10$$-$$8 $$\widehat z$$T. The value of electric field at this point is :

(speed of light = 3 $$\times$$ 108 ms$$-$$1)

$$\widehat x$$, $$\widehat y$$, $$\widehat z$$ are unit vectors along x, y and z directions.
A
2.6 $$\widehat x$$ V/m
B
$$-$$24 $$\widehat x$$ V/m
C
24 $$\widehat x$$ V/m
D
$$-$$2.6 $$\widehat y$$ V/m
2
JEE Main 2021 (Online) 16th March Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
For an electromagnetic wave travelling in free space, the relation between average energy densities due to electric (Ue) and magnetic (Um) fields is :
A
Ue = Um
B
Ue $$\ne$$ Um
C
Ue < Um
D
Ue > Um
3
JEE Main 2021 (Online) 24th February Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
Match List - I with List - II.

List I List II
(a) Source of microwave frequency (i) Radioactive decay of nucleus
(b) Source of infrared frequency (ii) Magnetron
(c) Source of Gamma Rays (iii) Inner shell electrons
(d) Source of X-rays (iv) Vibration of atoms and molecules
(v) LASER
(vi) RC circuit


Choose the correct answer from the options given below :
A
(a)-(vi), (b)-(v), (c)-(i), (d)-(iv)
B
(a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
C
(a)-(ii), (b)-(iv), (c)-(vi), (d)-(iii)
D
(a)-(vi), (b)-(iv), (c)-(i), (d)-(v)
4
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
For a plane electromagnetic wave, the magnetic field at a point x and time t is

$$\overrightarrow B \left( {x,t} \right)$$ = $$\left[ {1.2 \times {{10}^{ - 7}}\sin \left( {0.5 \times {{10}^3}x + 1.5 \times {{10}^{11}}t} \right)\widehat k} \right]$$ T

The instantaneous electric field $$\overrightarrow E $$ corresponding to $$\overrightarrow B $$ is :
(speed of light c = 3 × 108 ms–1)
A
$$\overrightarrow E \left( {x,t} \right) = \left[ {36\sin \left( {1 \times {{10}^3}x + 1.5 \times {{10}^{11}}t} \right)\widehat i} \right]$$ $${V \over m}$$
B
$$\overrightarrow E \left( {x,t} \right) = \left[ {36\sin \left( {0.5 \times {{10}^3}x + 1.5 \times {{10}^{11}}t} \right)\widehat k} \right]{V \over m}$$
C
$$\overrightarrow E \left( {x,t} \right) = \left[ {36\sin \left( {1 \times {{10}^3}x + 0.5 \times {{10}^{11}}t} \right)\widehat j} \right]{V \over m}$$
D
$$\overrightarrow E \left( {x,t} \right) = \left[ { - 36\sin \left( {0.5 \times {{10}^3}x + 1.5 \times {{10}^{11}}t} \right)\widehat j} \right]{V \over m}$$
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