In an electromagnetic wave in free space, the root mean square value of the electric field is \(E_{\text{rms}} = 6~\text{V/m}\). The peak value of the magnetic field is:
1. \(2.83\times 10^{-8}~\text{T}\)
2. \(0.70\times 10^{-8}~\text{T}\)
3. \(4.23\times 10^{-8}~\text{T}\)
4. \(1.41\times 10^{-8}~\text{T}\)
1. | wavelength is doubled and frequency becomes half |
2. | wavelength is halved and frequency remains unchanged |
3. | wavelength and frequency both remain unchanged |
4. | wavelength is doubled and frequency unchanged |
The charge of a parallel plate capacitor is varying as; \(q = q_{0} \sin\omega t\). The magnitude of displacement current through the capacitor is:
(the plate Area = \(A\), separation of plates = \(d\))
1. \(q_{0}\cos \left(\omega t \right)\)
2. \(q_{0} \omega \sin\omega t\)
3. \(q_{0} \omega \cos \omega t\)
4. \(\frac{q_{0} A \omega}{d} \cos \omega t\)
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. |
A variable frequency AC source is connected to a capacitor. Then on increasing the frequency:
1. | Both conduction current and displacement current will increase |
2. | Both conduction current and displacement current will decrease |
3. | Conduction current will increase and displacement current will decrease |
4. | Conduction current will decrease and displacement current will increase |
The electric field associated with an electromagnetic wave in vacuum is given by \(E=40 \cos \left(k z-6 \times 10^8 t\right)\), where \(E\), \(z\), and \(t\) are in volt/m, meter, and second respectively.
The value of the wave vector \(k\) would be:
1. \(2~\text{m}^{-1}\)
2. \(0.5~\text{m}^{-1}\)
3. \(6~\text{m}^{-1}\)
4. \(3~\text{m}^{-1}\)
Light with an average flux of \(20~\text{W/cm}^2\) falls on a non-reflecting surface at normal incidence having a surface area \(20~\text{cm}^2\). The energy received by the surface during time span of \(1\) minute is:
1. \(12\times 10^{3}~\text{J}\)
2. \(24\times 10^{3}~\text{J}\)
3. \(48\times 10^{3}~\text{J}\)
4. \(10\times 10^{3}~\text{J}\)
1. | the energy density in electric field is equal to energy density in magnetic field. |
2. | they travel with a speed equal to \(\dfrac{1}{\sqrt{\mu_0~ \varepsilon_0}} .\) |
3. | they originate from charges moving with uniform speed. |
4. | they are transverse in nature. |