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1
JEE Main 2021 (Online) 25th July Evening Shift
+4
-1
Two ions having same mass have charges in the ratio 1 : 2. They are projected normally in a uniform magnetic field with their speeds in the ratio 2 : 3. The ratio of the radii of their circular trajectories is :
A
1 : 4
B
4 : 3
C
3 : 1
D
2 : 3
2
JEE Main 2021 (Online) 25th July Morning Shift
+4
-1
A linearly polarized electromagnetic wave in vacuum is

$$E = 3.1\cos \left[ {(1.8)z - (5.4 \times {{10}^6})t} \right]\widehat iN/C$$

is incident normally on a perfectly reflecting wall at z = a. Choose the correct option
A
The wavelength is 5.4 m
B
The frequency of electromagnetic wave is 54 $$\times$$ 104 Hz.
C
The transmitted wave will be $$3.1\cos \left[ {(1.8)z - (5.4 \times {{10}^6})t} \right]\widehat iN/C$$
D
The reflected wave will be $$3.1\cos \left[ {(1.8)z + (5.4 \times {{10}^6})t} \right]\widehat iN/C$$
3
JEE Main 2021 (Online) 22th July Evening Shift
+4
-1
Choose the correct option
A
True dip is always equal to apparent dip.
B
True dip is not mathematically related to apparent dip.
C
True dip is less than the apparent dip.
D
True dip is always greater than the apparent dip.
4
JEE Main 2021 (Online) 22th July Evening Shift
+4
-1
Intensity of sunlight is observed as 0.092 Wm$$-$$2 at a point in free space. What will be the peak value of magnetic field at the point?

($${\varepsilon _0} = 8.85 \times {10^{ - 12}}{C^2}{N^{ - 1}}{m^{ - 2}}$$)
A
2.77 $$\times$$ 10$$-$$8 T
B
1.96 $$\times$$ 10$$-$$8 T
C
8.31 T
D
5.88 T
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