Q. No.
Which of the following statements about electromagnetic waves is/are correct:
A.
\(X\text-\)rays in a vacuum travel faster than light waves in a vacuum.
B.
The energy of a \(X\text-\)ray photon is greater than that of a light photon.
C.
Light can be polarised but \(X\text-\)rays cannot.
Choose the correct option from the given ones:
1. \(A\) and \(B\) only
2. B and \(C\) only
3. \(A,B,\) and \(C\) only
4. \(B\) only
2. B and \(C\) only
3. \(A,B,\) and \(C\) only
4. \(B\) only
(\(\rho\) = volume charge density, \(J\) = current density, \(m\) = pole strength, \(V\) = volume, \(S\) is a closed surface, and \(C\) is closed loop)
| 1. | \(\oint_S \vec{E} \cdot \overrightarrow{d S}=\frac{1}{\varepsilon_0} \int_V \rho d V\) |
| 2. | \(\oint_S \vec{B} \cdot \overrightarrow{d S}=\frac{m}{\mu_0}\) |
| 3. | \(\oint_S \vec{E} \cdot \overrightarrow{d l}=-\frac{d}{d t} \int_S \vec{B} \cdot \overrightarrow{d S}\) |
| 4. | \(\oint_S \vec{H} \cdot \overrightarrow{d S}=\int_C\left(\vec{J}+\frac{d}{d t}\left(\varepsilon_0 \vec{E}\right)\right) \cdot \overrightarrow{d S}\) |
\(E=E_{0}\sin\left ( kx-\omega t \right )\) and \(B=B_{0}\sin\left ( kx-\omega t \right ),\) then:
| 1. | \(E_0k = B_0 \omega\) |
| 2. | If the electric field is in the \(z\text-\)direction then the magnetic field should be in the \(-y\text-\)direction |
| 3. | Both 1 and 2 are correct |
| 4. | Only 1 is correct |
| 1. | \(20\) m | 2. | \(30\) m |
| 3. | \(40\) m | 4. | \(10\) m |
Which of the following electromagnetic waves has minimum frequency?
1. Radio waves
2. Infrared waves
3. Microwaves
4. X-rays
| 1. | \(1.873 \times 10^7~\text{V/s} \) |
| 2. | \(1.873 \times 10^8~\text{V/s}\) |
| 3. | \(1.873 \times 10^9~\text{V/s}\) |
| 4. | \(1.873 \times 10^{10}~\text{V/s}\) |
A lamp emits monochromatic green light uniformly in all directions. The lamp is \(3\%\) efficient in converting electrical power to electromagnetic waves and consumes \(100\) W of power. The amplitude of the electric field associated with the electromagnetic radiation at a distance of \(5\) m from the lamp will be:
1. \(1.34\) V/m
2. \(2.68\) V/m
3. \(4.02\) V/m
4. \(5.36\) V/m
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 |
Instantaneous displacement current of \(2.0~\text A\) is set up in the space between two parallel plates of \(1~\mu \text{F}\) capacitor. The rate of change in potential difference across the capacitor is:
1. \(3\times 10^{6}~\text{V/s}\)
2. \(4\times 10^{6}~\text{V/s}\)
3. \(2\times 10^{6}~\text{V/s}\)
4. None of these
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