A parallel plate capacitor with circular plates of radius 1 m has a capacitance of 1 nF. At t = 0, it is connected for charging in series with a resistor R = 1 M$\Omega$ across a 2V battery (as shown in the figure). Find the magnetic field at a point P, halfway between the centre and the periphery of the plates, after t = 10–3 s. (The charge on the capacitor at time t is (t) = CV[1 – exp (–t/$\tau$)], where the time constant $\tau$ is equal to CR.)

Subtopic:  Maxwell's Equations |
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Hints

A plane electromagnetic wave of frequency 25 MHz travels in free space along the x-direction. At a particular point in space and time, $$\vec{E_{0}}=6.3~ \hat{j}~V/m$$What is $$\vec{B_{0}}$$ at this point?
1. $$2.1\times 10^{-8} \hat{k}~\text{T}$$
2. $$1.2\times10^{-8} \hat{k}~\text{T}$$
3. $$2.1\times10^{-8} \hat{j}~\text{T}$$
4. $$1.2\times10^{-8} \hat{j}~\text{T}$$


Subtopic:  Properties of EM Waves |
77%
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Hints

The magnetic field in a plane electromagnetic wave is given by $$\mathrm{B}=\left(2 \times 10^{-7}\right) \mathrm{T} \sin \left(0.5 \times 10^3 \mathrm{x}+1.5 \times 10^{11} \mathrm{t}\right )$$. The wavelength and frequency of the wave are respectively:

 1 $$2.16 \mathrm{~cm}, 24.1 \mathrm{~GHz}$$ 2 $$0.29 \mathrm{~cm}, 13.7 \mathrm{~GHz}$$ 3 $$3.23 \mathrm{~cm}, 20.0 \mathrm{~GHz}$$ 4 $$1.26 \mathrm{~cm}, 23.9 \mathrm{~GHz}$$



Subtopic:  Properties of EM Waves |
70%
From NCERT
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NEET 2023 - Target Batch - Aryan Raj Singh
Hints
To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

The magnetic field in a plane electromagnetic wave is given by $$\mathrm{B}=\left(2 \times 10^{-7}\right) \mathrm{T} \sin \left(0.5 \times 10^3 \mathrm{x}+1.5 \times 10^{11} \mathrm{t}\right)$$. The expression for the electric field is:
1. $$\mathrm{E}_{\mathrm{z}}=60 \sin \left(0.5 \times 10^3 \mathrm{x}+1.5 \times 10^{11} \mathrm{t}\right) \mathrm{V} / \mathrm{m}$$
2. $$\mathrm{E}_{\mathrm{z}}=60 \sin \left(1.5 \times 10^3 \mathrm{x}+0.5 \times 10^{11} \mathrm{t}\right) \mathrm{V} / \mathrm{m}$$
3. $$\mathrm{E}_{\mathrm{z}}=55 \sin \left(0.5 \times 10^3 \mathrm{x}+1.5 \times 10^{11} \mathrm{t}\right) \mathrm{V} / \mathrm{m}$$
4. $$\mathrm{E}_{\mathrm{z}}=55 \sin \left(1.5 \times 10^3 \mathrm{x}+0.5 \times 10^{11} \mathrm{t}\right) \mathrm{V} / \mathrm{m}$$


Subtopic:  Properties of EM Waves |
81%
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Hints

Light with an energy flux of 18 W/cm2 falls on a non-reflecting surface at normal incidence. If the surface has an area of 20 cm2, what is the average force exerted on the surface during a 30 minute time span?

Subtopic:  Properties of EM Waves |
55%
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Hints
Assume a bulb of efficiency $$2.5\%$$ as a point source. The peak values of the electric field and magnetic field produced by the radiation coming from a $$100~\mathrm{W}$$ bulb at a distance of $$3~\mathrm{m}$$ are respectively:
 1 $$2.5 \mathrm{~V} / \mathrm{m}, ~2.2 \times 10^{-8} \mathrm{~T}$$ 2 $$3.6 \mathrm{~V} / \mathrm{m},~ 3.6 \mathrm{~T}$$ 3 $$4.07 \mathrm{~V} / \mathrm{m},~ 1.4 \times 10^{-8} \mathrm{~T}$$ 4 $$4.2 \mathrm{~V} / \mathrm{m}, ~3.4 \times 10^{-6} \mathrm{~T}$$