A magnetic field vector in an electromagnetic wave is represented by \(\vec{B}=B_0 \sin \left(2 \pi v t-\dfrac{2 \pi x}{\lambda}\right) \hat{j} .\) Its associated electric field vector is:
1. \(\vec{E}=-v \lambda B_0 \sin \left(2 \pi v t-\dfrac{2 \pi x}{\lambda}\right) \hat{k}\)
2. \(\vec{E}=-v \lambda B_0 \sin \left(2 \pi v t-\dfrac{2 \pi x}{\lambda}\right) \hat{i}\)
3. \(\vec{E}=v \lambda B_0 \sin \left(2 \pi v t-\dfrac{2 \pi x}{\lambda}\right) \hat{k}\)
4. \(\vec{E}=v \lambda B_0 \sin \left(2 \pi v t-\dfrac{2 \pi x}{\lambda}\right) \hat{i}\)
Subtopic:  Properties of EM Waves |
 63%
Level 2: 60%+
Please attempt this question first.
Hints
Please attempt this question first.

An electromagnetic wave travels in free space along the \(x\text-\)direction. At a particular point in space and time, \(\vec{B}=2 \times 10^{-7} \hat{j} ~\text{T}\) is associated with this wave. The value of corresponding electric field \(\vec{E}\) at this point is: (in \(\text{V/m}.\))
1. \(60 \hat{k}~ \)
2. \(-60 \hat{k} \)
3. \( 30 \hat{k}\)
4. \(-600 \hat{k}\)
Subtopic:  Properties of EM Waves |
 91%
Level 1: 80%+
Please attempt this question first.
Hints
Please attempt this question first.

For an electromagnetic wave propagating through vacuum, \(\vec{k},\vec{E}\) and \(\omega\) represent propagation vector, electric field and angular frequency, respectively. The magnetic field associated with this wave is represented by:
1. \(\dfrac{\vec{E} \times \vec{k}}{\omega}\)
2. \(\dfrac{\vec{k} \times \vec{E}}{\omega}\)
3. \(\omega(\vec{E} \times \vec{k})\)
4. \(\omega(\vec{k} \times \vec{E})\)
Subtopic:  Properties of EM Waves |
 57%
Level 3: 35%-60%
Please attempt this question first.
Hints
Please attempt this question first.

advertisementadvertisement

A point light source emits E.M. waves in free space. A detector, placed at a distance of \(L~\text{m},\) measures the intensity as \(I_0.\) The detector is now shifted to another location on the same spherical surface ensuring the angle between original location and new location as \(45^\circ\). The measured intensity at new location will be:
1. \(\dfrac{I_0}{4}\)
2. \( I_0\)
3. \(\dfrac{I_0}{\sqrt{2}} \)
4. \(\dfrac{I_0}{2}\)
Subtopic:  Properties of EM Waves |
 71%
Level 2: 60%+
Please attempt this question first.
Hints
Please attempt this question first.

An electromagnetic wave travelling in \(x\text-\)direction is described by field equation \({E}_y=300 \sin \omega\left(t-\dfrac{x}{{c}}\right)\). If the electron is restricted to move in \(y\text-\)direction only with speed of \(1.5\times 10^6~\text{m/s}\) then ratio of maximum electric and magnetic forces on the electron is:
1. \(200\)
2. \(150\)
3. \(400\)
4. \(300\)
Subtopic:  Properties of EM Waves |
 55%
Level 3: 35%-60%
Please attempt this question first.
Hints
Please attempt this question first.

A displacement current of \(4.0~\text A\) can be set up in the space between two parallel plates of \(6~\mu \text{F}\) capacitor. The rate of change of potential difference across the plates of the capacitor is nearly \(\alpha \times 10^6 ~\text{V/s}\). The value of \(\alpha\) is:
1. \(0.58\)
2. \(0.67\)
3. \(0.82\)
4. \(0.75\)
Subtopic:  Displacement Current |
 96%
Level 1: 80%+
Please attempt this question first.
Hints
Please attempt this question first.

advertisementadvertisement

Given below are two statements: 
Assertion (A): The electromagnetic wave exerts pressure on the surface on which they are allowed to fall.  
Reason (R): There is no mass associated with the electromagnetic waves.
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. (A) is False but (R) is True.
Subtopic:  Properties of EM Waves |
 73%
Level 2: 60%+
Please attempt this question first.
Hints
Please attempt this question first.

A monochromatic source of light operating at \(15~\text{kW}\) emits \(2.5 \times 10^{22}\) photons/s. The region of an electromagnetic spectrum to which the emitted electromagnetic radiation belongs to:
(Take \(h=6.6 \times 10^{-34} ~\text{J/s}\) and \(c=3 \times 10^8 ~\text{m/s}\)).
1. Microwave 
2. Infrared 
3. Visible 
4. Ultraviolet
Subtopic:  Electromagnetic Spectrum |
Level 4: Below 35%
Please attempt this question first.
Hints
Please attempt this question first.

The electric field a plane electromagnetic wave is given by :
\({E}_{y}=69 \sin \left[0.6 \times 10^3 {x}-1.8 \times 10^{11} {t}\right] ~\text{V/m}.\)
The expression for magnetic field associated with this electromagnetic wave is: (in T)
1. \(B_z=2.3 \times 10^{-7} \sin \left[0.6 \times 10^3 x-1.8 \times 10^{11} t\right]\)
2. \(B_z=2.3 \times 10^{-7} \sin \left[0.6 \times 10^3 x+1.8 \times 10^{11} t\right]\)
3. \(B_y=69 \sin \left[0.6 \times 10^3 x+1.8 \times 10^{11} t\right]\)
4. \( B_y=2.3 \times 10^{-7} \sin \left[0.6 \times 10^3 x-1.8 \times 10^{11} t\right] \)
Subtopic:  Properties of EM Waves |
 78%
Level 2: 60%+
Please attempt this question first.
Hints
Please attempt this question first.

advertisementadvertisement

An electromagnetic wave of frequency \(100~\text{MHz}\) propagates through a medium of conductivity, \(\sigma= 10~\text{mho/m}\). The ratio of maximum conducting current density to maximum displacement current density is:
\(\left[\text {Take}~ \dfrac{1}{4 \pi \varepsilon_0}=9 \times 10^9 ~\text{Nm}^2 / \text{C}^2\right] \)
1. \(1200\)
2. \(1400\)
3. \(1800\)
4. \(2000\)
Subtopic:  Displacement Current |
Level 3: 35%-60%
Please attempt this question first.
Hints
Please attempt this question first.