1
JEE Main 2021 (Online) 27th August Evening Shift
Numerical
+4
-1
A plane electromagnetic wave with frequency of 30 MHz travels in free space. At particular point in space and time, electric field is 6 V/m. The magnetic field at this point will be x $$\times$$ 10$$-$$8 T. The value of x is ___________.
2
JEE Main 2021 (Online) 26th August Morning Shift
Numerical
+4
-1
The electric field in a plane electromagnetic wave is given by

$$\overrightarrow E = 200\cos \left[ {\left( {{{0.5 \times {{10}^3}} \over m}} \right)x - \left( {1.5 \times {{10}^{11}}{{rad} \over s} \times t} \right)} \right]{V \over m}\widehat j$$. If this wave falls normally on a perfectly reflecting surface having an area of 100 cm2. If the radiation pressure exerted by the E.M. wave on the surface during a 10 minute exposure is $${x \over {{{10}^9}}}{N \over {{m^2}}}$$. Find the value of x .
3
JEE Main 2021 (Online) 17th March Evening Shift
Numerical
+4
-1
The electric field intensity produced by the radiation coming from a 100 W bulb at a distance of 3 m is E. The electric field intensity produced by the radiation coming from 60W at the same distance is $$\sqrt {{x \over 5}}$$E. Where the value of x = ____________.
4
JEE Main 2021 (Online) 17th March Evening Shift
Numerical
+4
-1
Seawater at a frequency f = 9 $$\times$$ 102 Hz, has permittivity $$\varepsilon$$ = 80$$\varepsilon$$0 and resistivity $$\rho$$ = 0.25 $$\Omega$$m. Imagine a parallel plate capacitor is immersed in seawater and is driven by an alternating voltage source V(t) = V0 sin(2$$\pi$$ft). Then the conduction current density becomes 10x times the displacement current density after time t = $${1 \over {800}}$$s. The value of x is _____________. (Given : $${1 \over {4\pi {\varepsilon _0}}} = 9 \times {10^9}$$ Nm2C$$-$$2)
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