Q. No.Consider the following statements about electromagnetic waves and choose the correct ones:
| S1: | Electromagnetic waves having wavelengths \(1000\) times smaller than light waves are called X-rays. |
| S2: | Ultraviolet waves are used in the treatment of swollen joints. |
| S3: | Alpha and gamma rays are not electromagnetic waves. |
| S4: | de-Broglie waves are not electromagnetic in nature. |
| S5: | Electromagnetic waves exhibit polarization while sound waves do not. |
| 1. | S1, S4, and S5 |
| 2. | S3, S4, and S5 |
| 3. | S1, S3, and S5 |
| 4. | S2, S3 and S4 |
Subtopic: Properties of EM Waves |
69%
Level 2: 60%+
Hints
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 |
78%
Level 2: 60%+
Hints
The region on the left of the \(y\)-axis \((x<0)\) represents vacuum, and the region on the right \((x>0)\) represents a transparent medium. An electromagnetic wave travelling along the \(x\)-axis given by:
\(\vec E_1(x,t)=E_1\hat j~\sin(\omega t-k_0x),\) where \(x<0,\)
is incident on to the medium on the right. The transmitted wave in the medium is:
\(\vec E_2(x,t)=E_2\hat j~\sin(\omega t-2k_0x),\) where \(x>0.\)
The refractive index of the medium is:
\(\vec E_1(x,t)=E_1\hat j~\sin(\omega t-k_0x),\) where \(x<0,\)
is incident on to the medium on the right. The transmitted wave in the medium is:
\(\vec E_2(x,t)=E_2\hat j~\sin(\omega t-2k_0x),\) where \(x>0.\)
The refractive index of the medium is:
| 1. | \(2\) | 2. | \(\sqrt2\) |
| 3. | \(4\) | 4. | \(2\sqrt2\) |
Subtopic: Properties of EM Waves |
67%
Level 2: 60%+
Hints
Given below are two statements:
| Assertion (A): | The fastest speed of propagation of any wave in any medium is the speed of electromagnetic waves in that medium. |
| Reason (R): | All signals can at most travel at the speed of light in a vacuum. |
| 1. | (A) is True but (R) is False. |
| 2. | (A) is False but (R) is True. |
| 3. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 4. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
Subtopic: Properties of EM Waves |
Level 3: 35%-60%
Hints
Given below are two statements:
| Statement I: | Electromagnetic waves propagate through all media with a speed \(c=\dfrac{1}{\sqrt{\varepsilon_0\mu_0}}.\) |
| Statement II: | Electromagnetic waves can undergo reflection and refraction. |
| 1. | Statement I is incorrect and Statement II is correct. |
| 2. | Both Statement I and Statement II are correct. |
| 3. | Both Statement I and Statement II are incorrect. |
| 4. | Statement I is correct and Statement II is incorrect. |
Subtopic: Properties of EM Waves |
55%
Level 3: 35%-60%
Hints
The electric field of an electromagnetic wave in free space is given by –
, where t and x are in seconds and metres respectively. It can be inferred that:
(a) The wavelength λ is 188.4 m
(b) The wave number k is 0.33 rad / m
(c) The wave amplitude is 10 V / m
(d) The wave is propagating along + x direction
Which one of the following pairs of statements is correct?
1. (a) and (b)
2. (b) and (c)
3. (c) and (d)
4. (a) and (c)
Subtopic: Properties of EM Waves |
54%
Level 3: 35%-60%
AIPMT - 2010
Hints
Assertion: Like light radiation, thermal radiations are also electromagnetic radiation.
Reason: The thermal radiations require no medium for propagation.
1. Both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
2. Both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion.
3. Assertion is true but Reason is false.
4. Both Assertion and Reason are false.
Reason: The thermal radiations require no medium for propagation.
1. Both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
2. Both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion.
3. Assertion is true but Reason is false.
4. Both Assertion and Reason are false.
Subtopic: Properties of EM Waves |
Level 3: 35%-60%
Hints
Assertion: Environmental damage has increased the amount of ozone in the atmosphere.
Reason: The increase of ozone increases the amount of ultraviolet radiation on earth.
1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but the reason is false.
4. Both assertion and reason are false.
Reason: The increase of ozone increases the amount of ultraviolet radiation on earth.
1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but the reason is false.
4. Both assertion and reason are false.
Subtopic: Properties of EM Waves |
69%
Level 2: 60%+
Hints
Assertion: If the earth did not have an atmosphere, its average surface temperature would be lower than what is now.
Reason: Greenhouse effect of the atmosphere would be absent if the earth did not have an atmosphere.
1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but the reason is false.
4. Both assertion and reason are false.
Reason: Greenhouse effect of the atmosphere would be absent if the earth did not have an atmosphere.
1. Both assertion and reason are true and the reason is the correct explanation of the assertion.
2. Both assertion and reason are true but the reason is not the correct explanation of the assertion.
3. Assertion is true but the reason is false.
4. Both assertion and reason are false.
Subtopic: Properties of EM Waves |
75%
Level 2: 60%+
Hints
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R):
In the light of the above statements choose the correct answer from the options given below:
| Assertion (A): | The energy of an electromagnetic wave is not equally distributed among the electric field and magnetic field. |
| Reason (R): | The amplitude of electric field E0 and magnetic field B0 are related by the relation \(E_0 ={B_0\over c}\), where c is the velocity of light. |
In the light of the above statements choose the correct answer from the options given below:
| 1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
| 3. | (A) is true but (R) is false. |
| 4. | Both (A) and (R) are false. |
Subtopic: Properties of EM Waves |
81%
Level 1: 80%+
Hints
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