Q. No.The speed of an electromagnetic wave in a medium of dielectric constant \(2.25\) and relative permeability \(4\) is approximately:
1. \(1\times 10^{8}\) m/s
2. \(2.5\times 10^{8}\) m/s
3. \(3\times 10^{8}\) m/s
4. \(2\times 10^{8}\) m/s
The figure shows a parallel plate capacitor being charged by a battery. If \(X\) and \(Y\) are two closed curves then during charging, \(\oint \vec{B}.d\vec{l}\) is zero along the curve:
1. \(X\) only
2. \(Y\) only
3. Both \(X\) & \(Y\)
4. Neither \(X\) nor \(Y\)
A larger parallel plate capacitor, whose plates have an area of \(1~\text{m}^2,\) separated from each other by \(1~\text{mm},\) is being charged at a rate of \(25.8~\text{V/s}.\) If the plates have a dielectric constant \(10,\) then the displacement current at this instant is:
1. \(25~\mu\text{A}\)
2. \(11~\mu\text{A}\)
3. \(2.2~\mu\text{A}\)
4. \(1.1~\mu\text{A}\)
| 1. | wavelength is \(2\) times and frequency becomes half. |
| 2. | wavelength is half and frequency remains unchanged. |
| 3. | wavelength and frequency both remain unchanged. |
| 4. | None of the above. |
\(\oint \vec{B} . \vec{dl} = \mu_{0} \left(i + \varepsilon_{0} . \frac{d \left(\phi\right)_{E}}{d t}\right)\) is a statement of:
1. Faraday's law of induction
2. Modified Ampere's law
3. Gauss's law of electricity
4. Gauss's law of magnetism
The most penetrating radiation out of the following is:
1. \(X\text-\)rays
2. \(\beta\text-\)rays
3. \(\alpha\text-\)rays
4. \(\gamma\text-\)rays
Which of the following statements is false regarding the properties of electromagnetic waves?
| 1. | Both electric and magnetic field vectors attain the maxima and minima at the same place and the same time |
| 2. | The energy in an electromagnetic wave is divided equally between electric and magnetic vectors |
| 3. | Both electric and magnetic field vectors are parallel to each other and perpendicular to the direction of propagation of the wave |
| 4. | These waves do not require any material medium for propagation |
Choose the correct option:
| 1. | The radiation in increasing order of frequency are radio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays. |
| 2. | The wavelength of colours in increasing order is violet, indigo, green, yellow, orange and red. |
| 3. | The speed of light is maximum in vacuum. |
| 4. | All options are correct. |
The magnetic field amplitude of an electromagnetic wave is \(2\times 10^{-7}~\text{T}\). Its electric field amplitude if the wave is travelling in free space is:
1. \(6~\text{Vm}^{-1}\)
2. \(60~\text{Vm}^{-1}\)
3. \(\frac{10}{6}~\text{Vm}^{-1}\)
4. None of these
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