
εeq=3Req=9i1=93=31
εeq=r11+r21r1ε1+r2ε2
εeq=21+1121+12=35
requ =32×1+6=320i2=41⇒i2i1=34
JEE Main 2025 — Physics Electromagnetism
Two cells of emf 1 V and 2 V and internal resistance 2Ω and 1Ω, respectively, are connected in series with an external resistance of 6Ω. The total current in the circuit is I1. Now the same two cells in parallel configuration are connected to same external resistance. In this case, the total current drawn is I2. The value of (I2I1) is 3x. The value of x is _____.
Held on 3 Apr 2025 · Verified 6 Jul 2026.
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A magnetic field vector in an electromagnetic wave is represented by $\vec{B}=B_0\sin\left(2\pi vt-\dfrac{2\pi x}{\lambda}\right)\hat{j}$. Its associated electric field vector is ______.
A plane electromagnetic wave is moving in free space with velocity $c=3 \times 10^{8} \mathrm{~m} / \mathrm{s}$ and its electric field is given as $\vec{E}=54 \sin (k z-\omega t) \hat{j} \mathrm{~V} / \mathrm{m}$, where $\hat{j}$ is the unit vector along $y$-axis. The magnetic field vector $\vec{B}$ of the wave is:
A charged particle moves in a uniform magnetic field. If the velocity is perpendicular to the field, the path of the particle is:
A monochromatic source of light operating at $15$ kW emits $2.5\times 10^{22}$ photons/s. The region of an electromagnetic spectrum to which the emitted electromagnetic radiation belongs to ________. (Take $h=6.6\times 10^{-34}$ J·s and $c=3\times 10^8$ m/s).
An electromagnetic wave of frequency 100 MHz propagates through a medium of conductivity, $\sigma=10 \mathrm{mho} / \mathrm{m}$. The ratio of maximum conduction current density to maximum displacement current density is $\_\_\_\_$. $\left[\text{Take }\frac{1}{4 \pi \epsilon_{\mathrm{o}}}=9 \times 10^{9} \mathrm{Nm}^{2} / \mathrm{C}^{2}\right]$
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