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Q. No.An EM wave of intensity \(I\) falls on a surface kept in a vacuum and exerts radiation pressure \(P\) on it. Which of the following are true?
| (a) | Radiation pressure is \(\frac{I}{c}\) if the wave is totally absorbed. |
| (b) | Radiation pressure is \(\frac{I}{c}\) if the wave is totally reflected. |
| (c) | Radiation pressure is \(\frac{2I}{c}\) if the wave is totally reflected. |
| (d) | Radiation pressure is in the range \(\frac{I}{c}<P<\frac{2I}{c}\) for real surfaces. |
Choose the correct one from the given options:
| 1. | a, b and c | 2. | b, c and d |
| 3. | a, c and d | 4. | c and d |
Subtopic: Properties of EM Waves |
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Level 2: 60%+
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One requires \(11~\text{eV}\) of energy to dissociate a carbon monoxide molecule into carbon and oxygen atoms. The minimum frequency of the appropriate electromagnetic radiation to achieve the dissociation lies in:
1. visible region.
2. infrared region.
3. ultraviolet region.
4. microwave region.
1. visible region.
2. infrared region.
3. ultraviolet region.
4. microwave region.
Subtopic: Electromagnetic Spectrum |
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Level 2: 60%+
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A linearly polarized electromagnetic wave given as \({E}=E_o \hat{{i}} \cos (k z-\omega \mathrm{t})\) is incident normally on a perfectly reflecting infinite wall at \(z=a\). Assuming that the material of the wall is optically inactive, the reflected wave will be given as
1. \({E}_r=-E_o \hat{{i}} \cos (k z-\omega \mathrm{t}).\)
2. \({E}_r=E_o \hat{{i}} \cos (k z+\omega {t})\).
3. \({E}_r=-E_o \hat{{i}} \cos (k z+\omega {t}) \)
4. \({E}_r=E_o \hat{{i}} \sin (k z-\omega {t}) \)
1. \({E}_r=-E_o \hat{{i}} \cos (k z-\omega \mathrm{t}).\)
2. \({E}_r=E_o \hat{{i}} \cos (k z+\omega {t})\).
3. \({E}_r=-E_o \hat{{i}} \cos (k z+\omega {t}) \)
4. \({E}_r=E_o \hat{{i}} \sin (k z-\omega {t}) \)
Subtopic: Properties of EM Waves |
Level 3: 35%-60%
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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. \(\sqrt{2} E\)
1. \(\frac{E}{2}\)
2. \(2 E\)
3. \(\frac{E}{\sqrt{2}}\)
4. \(\sqrt{2} E\)
Subtopic: Generation of EM Waves |
54%
Level 3: 35%-60%
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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. \({E} \times {B}\)
1. \({E}\)
2. \({B}\)
3. \({B} \times {E}\)
4. \({E} \times {B}\)
Subtopic: Properties of EM Waves |
96%
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. \( \sqrt{c}: 1\)
1. \( c: 1 \)
2. \( c^2: 1 \)
3. \( 1: 1 \)
4. \( \sqrt{c}: 1\)
Subtopic: Properties of EM Waves |
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Level 1: 80%+
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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.
1. \( \frac{1}{r^3} \)
2. \(\frac{1}{r^2} \)
3. \(\frac{1}{r}\)
4. remains constant.
Subtopic: Generation of EM Waves |
55%
Level 3: 35%-60%
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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)
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;
Choose the correct option:
1. (a), (d)
2. (a), (b), (c)
3. (b), (d)
4. (c), (d)
| (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) | \(\hat{{k}} \times \vec{E}=0, \hat{{k}} \times \vec{B}=0.\) |
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)
(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 |
78%
Level 2: 60%+
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