back to directory
NEET PHYSICSELECTROMAGNETIC WAVESEasy

Question

The electric and the magnetic field, associated with an electromagnetic wave, propagating along the +z+z-axis, can be represented by:

A

[E=E0k^,B=B0i^]\left[ \mathbf{E} = E_0 \hat{k}, \mathbf{B} = B_0 \hat{i} \right]

B

[E=E0j^,B=B0j^]\left[ \mathbf{E} = E_0 \hat{j}, \mathbf{B} = B_0 \hat{j} \right]

C

[E=E0j^,B=B0k^]\left[ \mathbf{E} = E_0 \hat{j}, \mathbf{B} = B_0 \hat{k} \right]

D

[E=E0i^,B=B0j^]\left[ \mathbf{E} = E_0 \hat{i}, \mathbf{B} = B_0 \hat{j} \right]

Step-by-Step Solution

Electromagnetic waves are transverse in nature, meaning the electric field (E\mathbf{E}), magnetic field (B\mathbf{B}), and the direction of propagation are mutually perpendicular. The direction of wave propagation is given by the direction of the vector cross product E×B\mathbf{E} \times \mathbf{B} .

Given that the wave propagates along the +z+z-axis (represented by unit vector k^\hat{k}), we must satisfy the condition: Direction of (E×B)=k^(\mathbf{E} \times \mathbf{B}) = \hat{k}.

Let's test the options:

  1. k^×i^=j^\hat{k} \times \hat{i} = \hat{j} (Propagates along yy-axis). Also, E\mathbf{E} cannot be along the direction of propagation.
  2. j^×j^=0\hat{j} \times \hat{j} = 0 (Fields cannot be parallel).
  3. j^×k^=i^\hat{j} \times \hat{k} = \hat{i} (Propagates along xx-axis).
  4. i^×j^=k^\hat{i} \times \hat{j} = \hat{k} (Propagates along zz-axis). This matches the given condition.

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from ELECTROMAGNETIC WAVES. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSELECTROMAGNETIC WAVESelectricmagneticassociatedelectromagneticpropagating

More ELECTROMAGNETIC WAVES Questions

View all

The energy of the EM wave is of the order of $15 \text{ keV}$. To which part of the spectrum does it belong?

A.X-rays
B.Infrared rays
C.Ultraviolet rays
D.$\gamma$-rays
EasySolve

Light with an average flux of 20 W/cm² falls on a non-reflecting surface at normal incidence having a surface area of 20 cm². The energy received by the surface during a time span of 1 minute is:

A.12 × 10³ J
B.24 × 10³ J
C.48 × 10³ J
D.10 × 10³ J
EasySolve

The ratio of the amplitude of the magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to:

A.the speed of light in vacuum
B.reciprocal of speed of light in vacuum
C.the ratio of magnetic permeability to the electric susceptibility of vacuum
D.unity
EasySolve

A parallel plate capacitor is charged by connecting it to a battery through a resistor. If $i$ is the current in the circuit, then in the gap between the plates:

A.A displacement current of magnitude equal to $i$ flows in the same direction as $i$.
B.A displacement current of magnitude equal to $i$ flows in the opposite direction to $i$.
C.A displacement current of magnitude greater than $i$ flows but it can be in any direction.
D.There is no current.
EasySolve

In an electromagnetic wave in free space the root mean square value of the electric field is $E_{rms} = 6$ V/m. The peak value of the magnetic field is:

A.$1.41 \times 10^{-8}$ T
B.$2.83 \times 10^{-8}$ T
C.$0.70 \times 10^{-8}$ T
D.$4.23 \times 10^{-8}$ T
MediumSolve

The electric field of an electromagnetic wave in free space is given by $\vec{E} = 10 \cos(10^7 t + kx) \hat{j}$ V/m, where $t$ and $x$ are in seconds and meters respectively. It can be inferred that: (1) The wavelength $\lambda$ is $188.4 \text{ m}$. (2) The wave number $k$ is $0.33 \text{ rad/m}$. (3) The wave amplitude is $10 \text{ V/m}$. (4) The wave is propagating along $+x$ direction. Which one of the following pairs of statements is correct?

A.(3) and (4)
B.(1) and (2)
C.(2) and (3)
D.(1) and (3)
MediumSolve

$\varepsilon_0$ and $\mu_0$ are the electric permittivity and magnetic permeability of free space respectively. If the corresponding quantities of a medium are $2\varepsilon_0$ and $1.5\mu_0$ respectively, the refractive index of the medium will nearly be:

A.$\sqrt{2}$
B.$\sqrt{3}$
C.3
D.2
MediumSolve

To produce an instantaneous displacement current of $2 \text{ mA}$ in the space between the parallel plates of a capacitor of capacitance $4 \text{ }\mu\text{F}$, the rate of change of applied variable potential difference $\left(\frac{dV}{dt}\right)$ must be:

A.$800 \text{ V/s}$
B.$500 \text{ V/s}$
C.$200 \text{ V/s}$
D.$400 \text{ V/s}$
EasySolve

This neet physics practice question is part of the TopperSquare free question bank. TopperSquare offers 15,000+ chapter-wise NEET MCQs across Physics, Chemistry, and Biology with detailed step-by-step explanations, full mock tests, NEET PYQs (2010–2024), and an AI-powered performance analytics dashboard. browse all neet practice questions → · practice physics sets →