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JEE Main 18 March 2021 Shift 1 Solved Paper
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© examsnet.com
Question : 4
Total: 90
A plane electromagnetic wave of frequency
100
M
H
z
is travelling in vacuum along the
x
-direction. At a particular point in space and time,
B
=
2.0
×
10
−
8
∧
k
T
(where,
∧
k
is unit vector along z-direction). What is
E
at this point?
[18 Mar 2021 Shift 1]
0.6
∧
j
V
/
m
6.0
∧
k
V
/
m
6.0
∧
j
V
/
m
0.6
∧
k
V
/
m
Validate
Solution:
Given,
f
=
100
M
H
z
B
=
(
2.0
×
10
−
8
)
∧
k
T
The speed of the light in free space,
c
=
(
3
×
10
s
)
∧
i
m
∕
s
(the direction of wave propagates in
x
-direction)
Magnitude of electric field,
E
=
B
c
=
2
×
10
−
8
×
3
×
10
8
⇒
E
=
6
V
/
m
If
∧
n
be the direction of
E
, then
∧
i
=
∧
n
×
∧
k
⇒
∧
n
=
∧
j
Hence, the electric field at this point is
6
∧
j
V
/
m
.
© examsnet.com
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