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)
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. |
1. (a, b, c)
2. (b, c, d)
3. (a, c, d)
4. (c, d)
Statement I: | Charged particles which undergo acceleration or deceleration radiate their energy away. |
Statement II: | Therefore, charged particles moving in circular paths in a uniform magnetic field should also radiate their energy. |
1. | Statement I is true, Statement II is true and Statement I implies Statement II. |
2. | Statement I is true, Statement II is true and Statement I does not imply Statement II. |
3. | Statement I is true, Statement II is false. |
4. | Statement I is false, Statement II is true. |
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). |
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 |
(A) | a varying sinusoidal current flowing through a capacitor |
(B) | an electric dipole, whose size (and magnitude) is oscillating with time |
(C) | a steady current flowing through a toroid |
1. | only (A) | 2. | only (B) |
3. | only (A) & (B) | 4. | (A), (B), (C) |
List -I (Electromagnetic waves) | List - II (Wavelength) | ||
(a) | AM radio waves | (i) | \(10^{-10}~\text{m}\) |
(b) | Microwaves | (ii) | \(10^{2} ~\text{m}\) |
(c) | Infrared radiation | (iii) | \(10^{-2} ~\text{m}\) |
(d) | \(X\)-rays | (iv) | \(10^{-4} ~\text{m}\) |
(a) | (b) | (c) | (d) | |
1. | (ii) | (iii) | (iv) | (i) |
2. | (iv) | (iii) | (ii) | (i) |
3. | (iii) | (ii) | (i) | (iv) |
4. | (iii) | (iv) | (ii) | (i) |
Assertion (A): | Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor does not change. |
Reason (R): | The displacement current arises in the region in which the electric field and hence the electric flux does not change with time. |
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. |