An EM wave radiates outwards from a dipole antenna, with \(E_0\) as the amplitude of its electric field vector. The electric field \(E_0\) which transports significant energy from the source falls off as:
1. \( \frac{1}{r^3} \)
2. \(\frac{1}{r^2} \)
3. \(\frac{1}{r}\)
4. remains constant.

Subtopic:  Generation of EM Waves |
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An electromognetic wave travels in vacuum along \(z\) direction: \({E}=\left(E_1 \hat{{i}}+E_2 \hat{{j}}\right) \cos (k z-\omega t)\). Choose the correct options from the following:
a. The associated magnetic field is given as \({B}=\frac{1}{{c}}\left(E_1 \hat{{i}}-E_2 \hat{{j}}\right) \cos (k z-\omega t)\)
b. The associated magnetic field is given as \({B}=\frac{1}{c}\left(E_1 \hat{{i}}-E_2 \hat{{j}}\right) \cos (k z-\omega \mathrm{t})\).
c. The given electromagnetic field is circularly polarised.
d. The given electromagnetic wave is plane polarised.
Choose the correct option:
1. (a), (d)
2. (a), (b), (c)
3. (b), (d)
4. (c), (d)
Subtopic:  Properties of EM Waves |
Level 3: 35%-60%
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An electromagnetic wave travelling along \(z\)-axis is given as: \(\vec{E}={E}_0 \cos (k z-\omega t). \) Choose the correct options from the following;
(a) The associated magnetic field is given as \(\vec{B}=\dfrac{1}{c} \hat{{k}} \times \vec{E}=\dfrac{1}{\omega}(\hat{{k}} \times \vec{E}).\)
(b) The electromagnetic field can be written in terms of the associated magnetic field as \(\vec{E}=c({B} \times \hat{{k}}).\)
(c) \(\hat{{k}} \cdot \vec{E}=0, \hat{{k}} \cdot \vec{B}=0.\)
(d) \(\hat{{k}} \times \vec{E}=0, \hat{{k}} \times \vec{B}=0.\)
Choose the correct option:
1. (a), (d)
2. (a), (b), (c)
3. (b), (d)
4. (c), (d)
Subtopic:  Properties of EM Waves |
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A plane electromagnetic wave propagating along \(x\) direction can have the following pairs of \(\vec{E}\) and \(\vec {B}\)
(a) \( E_x, B_y \)
(b) \( E_y, B_z\)
(c) \( B_x, E_y \)
(d) \( E_z, B_y\)
Choose the correct options:
1. (a), (d)
2. (a), (b), (c)
3. (b), (d)
4. (c), (d)
Subtopic:  Properties of EM Waves |
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Level 2: 60%+
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A charged particle oscillates about its mean equilibrium position with a frequency of \(10^9~\text{Hz}\). The electromagnetic waves produced:
a. will have frequency of \(10^9 ~\text{Hz} .\)
b. will have frequency of \(2 × 10^9~\text{Hz}.\)
c. will have a wavelength of \(0.3~\text{m}\).
d. fall in the region of radiowaves.
Choose the correct option:
1. (a), (d)
2. (a), (c), (d)
3. (b), (d)
4. (c), (d)
Subtopic:  Generation of EM Waves |
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The source of electromagnetic waves can be a charge
a. moving with a constant velocity.
b. moving in a circular orbit.
c. at rest.
d. falling in an electric field
Choose the correct option:
1. (a), (d)
2. (a), (b), (c)
3. (b), (d)
4. (c), (d)
Subtopic:  Generation of EM Waves |
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An EM wave of intensity I falls on a surface kept in vacuum and exerts radiation pressure p on it. Which of the following are true?
a. Radiation pressure is I/c if the wave is totally absorbed.
b. Radiation pressure is I/c if the wave is totally reflected.
c. Radiation pressure is 2I/c if the wave is totally reflected.
d. Radiation pressure is in the range I/c < p < 2I/c for real surfaces.
Choose the correct option:
1. (a), (d)
2. (a), (c), (d)
3. (b), (d)
4. (c), (d)
Subtopic:  Properties of EM Waves |
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Level 1: 80%+
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The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is
1. \( c: 1 \)
2. \( c^2: 1 \)
3. \( 1: 1 \)
4. \( \sqrt{c}: 1\)
Subtopic:  Properties of EM Waves |
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If \({E}\) and \({B}\) represent electric and magnetic field vectors of the electromagnetic wave, the direction of propagation of electromagnetic wave is along
1. \({E}\)
2. \({B}\)
3. \({B} \times {E}\)
4. \({E} \times {B}\)
Subtopic:  Properties of EM Waves |
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The electric field intensity produced by the radiations coming from \(100 ~\text{W}\) bulb at a \(3~\text{m}\) distance is \(E\). The electric field intensity produced by the radiations coming from \(50 ~\text{W}\) bulb at the same distance is:
1. \(\frac{E}{2}\)
2. \(2 E\)
3. \(\frac{E}{\sqrt{2}}\)
4. \(\sqrt{2} E\)
Subtopic:  Generation of EM Waves |
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