1
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)
2
JEE Main 2021 (Online) 17th March Morning Shift
Numerical
+4
-1
If 2.5 $$\times$$ 10$$-$$6 N average force is exerted by a light wave on a non-reflecting surface of 30 cm2 area during 40 minutes of time span, the energy flux of light just before it falls on the surface is ___________ W/cm2. (Round off to the Nearest Integer)

(Assume complete absorption and normal incidence conditions are there)
3
JEE Main 2021 (Online) 26th February Morning Shift
Numerical
+4
-1
A radiation is emitted by 1000W bulb and it generates an electric field and magnetic field at P, placed at a distance of 2m. The efficiency of the bulb is 1.25%. The value of peak electric field at P is x $$\times$$ 10$$-$$1 V/m. Value of x is ___________. (Rounded off to the nearest integer) [Take $${\varepsilon _0} = 8.85 \times {10^{ - 12}}$$ C2N$$-$$1 m$$-$$2, c = $$3 \times {10^8}$$ ms$$-$$1]
4
JEE Main 2021 (Online) 25th February Evening Shift
Numerical
+4
-1
The peak electric field produced by the radiation coming from the 8W bulb at a distance of 10 m is $${x \over {10}}\sqrt {{{{\mu _0}c} \over \pi }} {V \over m}$$. The efficiency of the bulb is 10% and it is a point source. The value of x is ___________.