List of top Physics Questions on Electromagnetic waves asked in JEE Main

If electric field intensity of a uniform plane electromagnetic wave is given as
\(E = -301.6 \sin(kz - \omega t) \hat{a}_x + 452.4 \sin(k\omega - \omega t) \hat{a}_y \, \frac{V}{m}\)
Then, magnetic intensity ‘H’ of this wave in Am–1 will be :
[Given : Speed of light in vacuum c = 3 × 108ms–1, Permeability of vacuum \(\mu_0 = 4\pi \times 10^{-7}\) NA–2]
In free space, an electromagnetic wave of 3 GHz frequency strikes over the edge of an object of size \(\frac{\lambda}{100}\), where λ is the wavelength of the wave in free space. The phenomenon, which happens there will be

Identify the correct statements from the following descriptions of various properties of electromagnetic waves.
(A) In a plane electromagnetic wave electric field and magnetic field must be perpendicular to each other and direction of propagation of wave should be along electric field or magnetic field.
(B) The energy in electromagnetic wave is divided equally between electric and magnetic fields.
(C) Both electric field and magnetic field are parallel to each other and perpendicular to the direction of propagation of wave.
(D) The electric field, magnetic field and direction of propagation of wave must be perpendicular to each other.
(E) The ratio of amplitude of magnetic field to the amplitude of electric field is equal to speed of light.

Choose the most appropriate answer from the options given below

With reference to the observations in photo-electric effect, identify the correct statements from below:
(A) The square of maximum velocity of photoelectrons varies linearly with frequency of incident light.
(B) The value of saturation current increases on moving the source of light away from the metal surface.
(C) The maximum kinetic energy of photo-electrons decreases on decreasing the power of LED (Light emitting diode) source of light.
(D) The immediate emission of photo-electrons out of metal surface can not be explained by particle nature of light/electromagnetic waves.
(E) Existence of threshold wavelength can not be explained by wave nature of light/electromagnetic waves.

Choose the correct answer from the options given below.

A square wave of the modulating signal is shown in the figure. The carrier wave is given by C(t) = 5 sin(8πt) Volt. The modulation index is

Fig.
A beam of light travelling along X-axis is described by the electric field Ey = 900sin ω(t – x/c). The ratio of electric force to magnetic force on a charge q moving along Y-axis with a speed of 3 × 107 ms–1 will be :
(Given speed of light = 3 × 108 ms–1)
An EM wave propagating in x-direction has a wavelength of 8 mm. The electric field vibrating y-direction has maximum magnitude of 60 Vm–1. Choose the correct equations for electric and magnetic field if the EM wave is propagating in vacuum:
Find the modulation index of an AM wave having 8 V variation where maximum amplitude of the AM wave is 9 V.

Amplitude modulated wave is represented by VAM = 10[1 + 0.4 cos(2π × 104t] cos(2π × 107t). The total bandwidth of the amplitude modulated wave is :

Match List-I with List-II:

List-IList-II
(a) UV rays(i) Diagnostic tool in medicine
(b) X-rays(ii) Water purification
(c) Microwave(iii) Communication, Radar
(d) Infrared wave(iv) Improving visibility in foggy days

Choose the correct answer from the options given below :

The speed of a transverse wave passing through a string of length 50 cm and mass 10 g is 60 ms–1. The area of cross-section of the wire is 2.0 mm2 and its Young’s modulus is 1.2 × 1011 Nm–2. The extension of the wire over its natural length due to its tension will be x × 10–5 m. The value of x is _____.
A sinusoidal wave y(t) = 40sin(10 × 106 πt) is amplitude modulated by another sinusoidal wave x(t) = 20sin(1000πt). The amplitude of minimum frequency component of modulated signal is:

Match List I with List II

 List I List II
AFacsimileIStatic Document Image
BGuided media ChannelIILocal Broadcast Radio
CFrequency ModulationIIIRectangular wave
DDigital SingleIVOptical Fiber
Which is the correct ascending order of wavelengths?
Sun light falls normally on a surface of area \(36 cm^2\) and exerts an average force of \(7.2 × 10^{–9} N\) within a time period of \(20 minutes\). Considering a case of complete absorption, the energy flux of incident light is

The electric field in an electromagnetic wave is given by \(E = 56.5\ sin ω(t – \frac xc)\ NC^{–1}\). Find the intensity of the wave if it is propagating along x-axis in the free space. (Given \(∈_0 = 8.85 × 10^{–12} C^2N^{–1}m^{–2}\))

The TV transmission tower at a particular station has a height of 125 m. For doubling the coverage of its range, the height of the tower should be increased by
A plane electromagnetic wave is propagating along the direction $\frac{\hat{i}+\hat{i}}{\sqrt{2}},$ with its polarization along the direction $\hat{k}.$ The correct form of the magnetic field of the wave would be (here $B_0$ is an appropriate constant):
The magnetic field of an electromagnetic wave is given by : $\vec{B} =1.6 \times10^{-6} \cos\left(2\times10^{7} z +6 \times10^{15}t\right)\left(2\hat{i} +\hat{j}\right) \frac{Wb}{m^{2}} $ The associated electric field will be :-
A $27\, mW$ laser beam has a cross-sectional area of $10 \; mm^2$. The magnitude of the maximum electric field in this electromagnetic wave is given by [Given permittivity of space $\in_0 = 9 \times 10^{-12} $ SI units, Speed of light $c = 3 \times 10^8 \; m/s$] :
A plane electromagnetic wave travels in free space along the x-direction. The electric field component of the wave at a particular point of space and time is $E = 6 \; V \; m^{-1}$ along y-direction. Its corresponding magnetic field component, B would be :
The magnetic field of a plane electromagnetic wave is given by $\vec{B} = B_0 \hat{i} [cos (kz - \omega t)] + B_1 \hat{j} cps (kz + \omega t).$ where B$_0 = 3 � 10^{-5} T$ and B$_1 = 2 � 10^{-6}$ T. The rms value of the force experienced by a stationary charge Q = 10 C at z = 0 is closest to :
The self induced emf of a coil is $25$ volts. When the current in it is changed at uniform rate from $10\, A$ to $25\, A$ in $1s$, the change in the energy of the inductance is :
A plane polarized monochromatic $EM $ wave is traveling in vacuum along $z$ direction such that at $t = t_1$ it is found that the electric field is zero at a spatial point $z_1$. The next zero that occurs in its neighbourhood is at $z_2$. The frequency of the electromagnetic wave is :
A plane electromagnetic wave of wavelength $\lambda$ has an intensity I. It is propagating along the positive Y-direction. The allowed expressions for the electric and magnetic fields are given by :