Physics · Electromagnetic Waves

JEE Main 2025 — 29 January, Evening Shift — Question 38

A parallel plate capacitor consisting of two circular plates of radius 10 cm is being charged by a constant current of 0.15 A . If the rate of change of potential difference between the plates is $7 \times 10^{8}$

$\mathrm{V} / \mathrm{s}$ then the integer value of the distance between the parallel plates is - $\left(\right.$

Take, $\left.\epsilon_{0}=9 \times 10^{-12} \frac{\mathrm{~F}}{\mathrm{~m}}, \pi=\frac{22}{7}\right)$

$\qquad$ $\mu \mathrm{m}$ .

Answer: 1320

Numerical answer — enter this value.

Step-by-step solution

$V=\frac{Q}{C}=\frac{i t}{\left(\frac{\epsilon_{0} A}{d}\right)}=\frac{i t d}{\epsilon_{0}\left(\pi r^{2}\right)}$ $\Rightarrow \mathrm{d}=\frac{\in_{0}\left(\pi \mathrm{r}^{2}\right)}{\mathrm{i}}\left(\frac{\mathrm{v}}{\mathrm{t}}\right)$

$=\frac{\left(9 \times 10^{-12}\right)\left(\frac{22}{7}\right)(0.1)^{2}}{0.15}\left(7 \times 10^{8}\right) \mathrm{m}$ $\mathrm{d}=1320 \mu \mathrm{~m}$

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Exam: JEE Main 2025
Paper: 29 January, Evening Shift
Subject: Physics
Chapter: Electromagnetic Waves
Topic: Displacement Current and Equation of EM Waves

A plane electromagnetic wave propagates along the +x direction in free space. The components of the electric field, vecE and magnetic…

Answer: 1320

Step-by-step solution

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