The energy density of the electromagnetic wave in vacuum is given by the relation:
1.
2.
3.
4.
A lamp radiates power uniformly in all directions. The amplitude of electric field strength at a distance r from it is:
1.
2.
3.
4.
The intensity of visible radiation at a distance of 1 m from a bulb of 100 W which converts only 5% of its power into light, is:
1. 0.4 W/m2
2. 0.5 W/m2
3. 0.1 W/m2
4. 0.01 W/m2
Which of the following statements about electromagnetic waves is/are correct:
A. | X-rays in vacuum travel faster than light waves in vacuum. |
B. | The energy of an X-ray photon is greater than that of a light photon. |
C. | Light can be polarised but X-ray cannot. |
1. A and B
2. B and C
3. A, B and C
4. B only
Which of the following is
not Maxwell's equation?
(= volume charge density, J = current density, m = pole strength, V = volume, S is 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. | \(\oint_s \vec{H} \cdot \overrightarrow{d S}=\int_c\left(\vec{J}+\frac{d}{d t}\left(\varepsilon_0 \vec{E}\right)\right) \cdot \overrightarrow{d S}\) |
The S.I. unit of displacement current is:
1. Henry
2. Coulomb
3. Ampere
4. Farad
If an electromagnetic wave going through a medium is given by;
\(E=E_{0}sin\left ( kx-\omega t \right )\) and \(B=B_{0}sin\left ( kx-\omega t \right ),\) then:
1. | |
2. | If the electric field is in the z-direction then the magnetic field should be in the -y direction |
3. | Both 1 and 2 are correct |
4. | Only 1 is correct |
Consider an electric charge oscillating with a frequency of 10 MHz. The radiation emitted will have a wavelength equal to:
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
A parallel plate capacitor consists of two circular plates each of radius 12 cm and separated by 5.0 mm. The capacitor is being charged by an external source. The charging current is constant and is equal to 0.15 A. The rate of change of the potential difference between the plates will be:
1. | \(1.873 \times 10^7 \mathrm{~V} / \mathrm{s}\) |
2. | \(1.873 \times 10^8 \mathrm{~V} / \mathrm{s}\) |
3. | \(1.873 \times 10^9 \mathrm{~V} / \mathrm{s}\) |
4. | \(1.873 \times 10^{10} \mathrm{~V} / \mathrm{s}\) |