Physics M.C.Q (1 Marks)

For an electromagnetic wave,electric field, magnetic field and direction of propagation are mutually perpendicular to each other. We can have a region in which electric and magnetic fields are applied at an angle with each other. In transmission lines Different modes exist. In transverse electric $(TE)$ mode$-$no electric field exist in the direction of propagation. These are sometimes called $H$ modes because there is only a magnetic field along the direction of propagation $($His the conventional symbol for magnetic field$).$

Electromagnet waves have electric field as well as magnetic field which are perpendicular to each other and the electromagnetic waves propagate in a direction
which is perpendicular to both the fields.
Thus the propagation vector of $EM$ waves $\overrightarrow{\text{k}}=\overrightarrow{\text{E}}\times\overrightarrow{\text{B}}$

Axis of propagation always lie perpendicular to the plane of vibrations, therefor angle between them is $\frac{\pi}{2}$

The compass needle deflects due to the presence of the magnetic field. Inside the capacitor, a magnetic field is produced when there is a changing electric field inside it. As the capacitor is connected across the battery, the charge on its plates at a certain time tis given by,
$\text{Q}=\text{CV}\Big(1-\text{e}^{-\tau/\text{RC}}\Big),$
$Q =$ Charge developed on the plates of the capacitor.
$R =$ Resistance of the resistor connected in series with the capacitor.
$C =$ Capacitance of the capacitor.
$V =$ Potential difference of the battery.
The time constant of the capacitor is given, $\tau=\text{RC}$
The capacitor keeps on charging up to the time $\tau$. The development of charge on the plates will be gradual after $​​\tau=\text{RC}$ The change in electric field will be up to the time the charge is developing on the plates of the capacitor. Thus, the compass needle deflects and gradually comes to the original position in a time that is large compared to the time constant.

Key concept: A changing electric field produces a changing magnetic field and vice versa which gives rise to a transverse wave known as electromagnetic wave. The time varying electric and magnetic field are mutually perpendicular to each other and also perpendicular to the direction of propagation of this wave. The electric vector is responsible for the optical effects of an $EM$ wave and is called the light vector.


The direction of propagation of electromagnetic wave is perpendicular to both electric field vector $(\vec{\text{E}})$ and $\vec{\text{B}}$ magnetic field vector $B$, i.e., in the direction of $\vec{\text{E}}\times\vec{\text{B}}$.
Here, elecromagnetic wave is along the $z-$direction which is given by the cross product of $E$ and $B.$

Time period, $\text{T}=\frac{1}{\text{v}}$
$\text{T}=\frac{1}{40\times10^6}$
$\Rightarrow\text{T}=0.25\mu\text{s}$

Human eye is sensitive to light of wavelength $\rightarrow \lambda=5550$ angstrom.
So its frequency is $v =\frac{ c }{\lambda}$
$v=\frac{5550}{3 \times 10^8} \times 10^{-10}$
$v=5.405 \times 10^{14} Hz$

All the longitudinal waves like sound etc cannot be polarized because the motion of the particles is already in one dimension that is the direction of propagation of wave.
Thus all the transverse waves like electromagnetic waves can be polarized.
Thus, $(B)$ Ultrasonic waves being sound waves having frequency greater than $20\ kHz$ but being longitudinal in nature cannot be polarized

Light waves and $X-$rays are electromagnetic waves.

$e = E \times B$, direction of propagation is always perpendicular to plane of $E$ and $B$. It will be positive in x-direction.

Radiation pressure is given by $\text{P}_\text{R}=\frac{(1+\alpha)\text{I}}{\text{C}}$
where α is the coefficient of reflection of the surface.
For completely reflecting surface $\alpha=1$
For completely absorbing surface $\alpha=0$
So, radiation pressure depends on the nature of surface on which the light is falling but independent of wavelength of light falling.

Microwaves have wavelength around $10\ cm.$

The wave equation for a plane electric wave traveling in the $x$ direction in space is
$\frac{\delta^2\text{E}}{\delta^2\text{y}}=\frac{1}{\text{c}^2}\frac{\delta^2\text{E}}{\delta\text{t}^2}$
with the same form applying to the magnetic field wave in a plane perpendicular the electric field. Both the electric field and the magnetic field are perpendicular to the direction of travel $y.$

An accelerated charge is the source of electromagnetic waves $\text{(EMWs).}$ When the charge is in a circular motion, the direction of its velocity continuously changes and thus it is in accelerated motion and produces $\text{EMWs.}$
A charge falling in an electric field is accelerated by the electric force and thus produces $\text{EMWs.}$

For any given medium, the speed $(c)$ of an electromagnetic wave is given by,
$\text{C}=\text{v}\lambda$
Where,
$V =$ Frequency of the electromagnetic wave.
$\lambda=$ wavelength of the electromagnetic wave.
As the frequency and wavelength are changed, the speed of the electromagnetic wave changes. So, the speed of an electromagnetic wave is not same for all wavelengths and all frequencies in any medium. The velocity of an electromagnetic wave changes with change in medium. Also, the speed of an electromagnetic wave is same for all the intensities in any medium.

The ratio of frequencies of $UV$ rays and $IR$ rays in the glass is more than $1$. This is because the frequency of $UV$ rays is greater than that of infrared rays. This situation is applicable in glass or vacuum or air.

As we know, $\text{E}\propto\text{R}^{-2}$
Therefore, $\text{E}(\text{R}=5)=\frac{500}{10^{-2}}5^{-2}=\frac{2000\text{V}}{\text{m}}$

For electromagnetic waves $E$ and $B$ are always perpendicular to each other and perpendicular to the direction of propagation. The direction of propagation is the direction of $E \times B.$
The direction of propagation of the wave is the direction of propagation of its energy and power.

A diode antenna radiates the electromagnetic waves outwards. The amplitude of electric field vector $\left(E_0\right)$ which transports significant energy from the source falls intensity inversely as the distance $(r)$ from the antenna, i.e., $E _0 \propto \frac{1}{ r }$.

In a capacitor of capacitance $C,$
$\text{V}=\frac{\text{q}}{\text{C}}$
$\Rightarrow\frac{\text{dV}}{\text{dt}}=\frac{\text{i}}{\text{C}}=\frac{1\text{A}}{1\mu\text{F}}=\frac{10^6\text{V}}{\text{s}}$

The general equation of an electromagnetic wave is $B = A \sin ( kx +\omega t )$
Comparing this equation with the given equation, $A =2 \times 10^{-7}, k =10^3$ and $\omega=1.5 \times 10^{12}$
So, $10^3=\frac{2 \pi}{\lambda}$
or $\lambda=6.28 \times 10^{-3} m=6.28 mm$

The same amount of energy passes through equal areas parallel to the $yz$ plane as the wave travels in the $+x$ direction, so the amplitude and the intensity, which is proportional to the square of the amplitude, do not change.

$\text{B}=\frac{\text{E}}{\text{C}}$
$=\frac{9.3}{3\times10^8}$
$=3.1\times10^{-8}$

$\text{k}=\frac{2\pi}{\lambda}$
$\omega=\frac{2\pi\text{c}}{\lambda},$ where c is the velocity of light
Hence, $=\frac{\text{k}}{2\pi}=\frac{\omega}{2\pi\text{c}}$
$\Rightarrow\frac{\text{k}}{\omega}$ is independent of the wavelength.

Velocity of light in a medium,
$\text{c}=\frac{1}{\sqrt{\mu_0\in_0\mu_\text{r}\in_\text{r}}}=\frac{1}{\mu_0\in_0}$

As we know, velocity of electromagnetic wave,
$\text{c}=\frac{1}{\sqrt{\mu_0\in_0}}=\frac{3\times10^8\text{m}}{\text{s}}$
which is constant
So It is independent of amplitude of electromagnetic wave, frequency and wavelength of electromagnetic wave.
so none of the above is correct.

Electromagnetic wave is a transverse wave that means the electric and magnetic field associated to it will not only be perpendicular to each other but will also be
perpendicular to the direction in which the wave travels.
So, if waves travel along $\hat{\text{k}}$ direction then the electric and the magnetic field will be along $\hat{\text{i}}$ and $\hat{\text{j}}$​ directions.

For a capacitor, we have:
$Q = CV$
If $Q$ is changing, there will be a current in capacitor plates,
$\text{I}=\frac{\text{dQ}}{\text{dt}}=\frac{\text{CdV}}{\text{dt}}$when voltage across the capacitor is constant, $\frac{\text{dV}}{\text{dt}}=0$
therefore,$ I = 0$
It implies that, for a $DC ($constant$)$ voltage, the capacitor current is zero.
Hence, for a $DC$ source the conduction current and displacement current $($capacitor current$)$ are not same.
Whereas, by Maxwell's equation for a time varying voltage $(AC$ voltage$),$ both conduction and displacement currents are same.

When frequency of microwave matches with frequency of water molecules i.e., resonant condition. Maximum energy is transferred to water molecules as their $K.E.$ energy.

Any stationary charge produce static electric field. And the field strength is given by:
$r$, is the radial distance from the point charge.
$Q,$ is the charge in Coulomb.
When electric charge oscillates electric field at any point also oscillates.And according to Maxwell's equations varying electric field produces magnetic field and an oscillating electric field produces oscillating magnetic field. This thing is used in antennas in which oscillating current of certain frequency produces oscillating electric and magnetic field which propagates through space $($electromagnetic waves$).$

Electromagnetic wave $V=3 \times 10^8 m / s$
Given frequency $(f) =10^9 Hz$
$\text{V}=\text{f}\lambda$
$\lambda=\frac{\text{V}}{\text{f}}$
$=\frac{3 \times 10^8} {10^9}$
$​= 0.3m$

An accelerated charge is the source of electromagnetic waves $\text{(EMWs)}$. When the charge is in a circular motion, the direction of its velocity continuously changes and thus it is in accelerated motion and produces $\text{EMWs}$. A charge falling in an electric field is accelerated by the electric force and thus produces $\text{EMWs.}$

Velocity of $EM$ wave $\text{v}=\frac{3\times10^8\text{m}}{\text{s}}$
Electric field vector $\text{E}=\frac{6\text{V}}{\text{m}}$
Thus magnetic field vector $\text{B}=\frac{\text{E}}{\text{v}}$
$\therefore\text{B}=\frac{6}{3\times10^8}=2\times10^{-8}\text{T}$

$v \rightarrow 2 vhv - hv v _0= KG _{\max }$
$So , KG _{\max }>2 KG _{\max }$
as $h v_0$ is constant

The speed of light, $\text{C}=\frac{1}{\sqrt{\mu_0\in_0}}$
The dimensions of $\frac{1}{\sqrt{\mu_0\in_0}}$ are of velocity, i.e., $\frac{\text{L}}{\text{T}}$
Therefore, $\frac{1}{\in_0\mu_0}$ will have dimensions $\frac{\text{L}^2}{\text{T}^2}$

According to Maxwell an accelerated charge produces a sinusoidal time varying magnetic field which in turn produces a time varying electric field .The two fields so produced are mutually perpendicular to each other and constitute an electromagnetic wave and propagate in space in the direction perpendicular to both the fields. An $AM$ wave is also an electromagnetic wave therefore its magnetic field component would be parallel to ground and perpendicular to the direction of propogation.

The matter$-$wave picture of electromagnetic wave/radiation elegantly incorporated the Heisenberg uncertainty principle.

Plane of polarization is a confinement of the electric/ magnetic field vector to a given plane along the direction of propagation. Therefore angle between them is $0^\circ .$

Radio Waves are generally in the frequency range $➔ 500\ kHz$ to $1000\ MHz$. Radio waves are used for long$-$distance communication, such as in television, mobiles, and radios. These devices receive radio waves and convert them to mechanical vibrations in the speaker to create sound waves.

The phase difference between electric and magnetic fields in an electromagnetic wave is$\pi$.

$X-$Rays are used to investigate the structure of solids.

The same amount of energy passes through equal areas parallel to the $yz$ plane as the wave travels in the $+x$ direction, so the amplitude and the intensity, which is proportional to the square of the amplitude, do not change.

Maxwell added the concept of displacement current in AMpere Circuit Law which governs the conduction in the wire of conduction current. After the deviation compass between capacitor Maxwell thought of magnetic lines which would be the result of varying current known as displacement current. So by continuing the displacement in Amperes law, Maxwell was able to show the result of Amperes conduction in circuit moving electrons and also the result of faraday generation of $ME$ waves.

Displacement current inside a capacitor is given by:-
$\text{i}_\text{d}=\in_0\frac{\phi\text{E}}{\text{dt}}$
where $\phi_\text{E}$​ is the electric flux inside the capacitor
The displacement current is developed inside a capacitor when there is a change in the electric flux linked with the capacitor.
The change in electric flux can occur in both the cases either the charge increases or decreases on the capacitor. This will lead to a change in flux linked with the coil.

The plane of polarisations is that plane in which there is no vibration. While a plane including the direction of light propagation and the direction of electric field is called the plane of vibration. The angle between them is $90^\circ .$

According to Ampere$-$Maxwell's Law, a magnetic field is produced due to the conduction current in a conductor and the displacement current. The conduction current is actually the motion of the charge. The displacement current is due to the changing electric field. The displacement current is given by,
$\text{i}_\text{d}=\in_0\frac{\text{d}\phi_\text{E}}{\text{dt}}$ $\big(\because\phi_\text{E}$ is the electric flux$\big)$
Thus, the magnetic field is produced by the moving charge as well as the electric field.

Key concept: When a wave is reflected from a denser medium or perfectly reflecting wall made with optically inactive material, then the type of wave doesn't change but only its phase changes by $180^\circ $ or $\hat{\text{I}}€$ radian.

The electric field is always perpendicular to the magnetic field, and both fields are directed at right$-$angles to the direction of propagation of the wave. In fact, the wave propagates in the direction $\overrightarrow{\text{E}}\times\overrightarrow{\text{B}}$ Electromagnetic waves are clearly a type of transverse wave.

The energy of electromagnetic waves is directly proportional to the frequency of the electromagnetic waves. So the order of frequency is given as:
$v_{\text {micro }} < v_{\text {infrared }}$ Since $E=h v$
$\rightarrow E \propto v$
The order of energy is as follows:
$E _{\text {micro }} < E _{\text {infrared }} < E _{\text {visible }} < E _{\text {ultraviolet }} < E _{\text {gamma }}$

Intensity or power per unit area of the radiations,
$P = pv$
$\Rightarrow\text{P}=\frac{\text{P}}{\text{v}}=\frac{0.5}{3\times10^8}=\frac{0.166\times10^{-8}\text{N}}{\text{m}^2}$

According to Maxwell's hypothesis, a displacement current will flow through a capacitor when the potential difference across its plates is varying.
Thus a varying electric field will exist between the plates and this displacement current is same in magnitude to the current flowing in outer circuit.
Here, the current in the outer circuit is $0.15 A$. Thus $0.15A$ will be the displacement current.

Light consists of electric and magnetic field that are perpendicular $90^\circ $ to each other.
$\text{APPOACH}$ by example
Electric field inside plates. The magnetic field this given rise to via the displacement current is along the perimeter of the circle parallel to capauatates plates.
So $B$ and $E$ are perpendicular in this case.

electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields that propagate at the speed of light through a vaccum. The oscillations of the two fields are perpendicular to each other and perpendicular to the direction of energy and wave propagation, forming a transverse wave. so if propogation is along $Y-$direction ,Electric field will be along $X$ or $Z$, if it is along $Z -$direction than Magnetic field has to be in $X -$direction.

The communication and broadcasting following the base on generation, propagation, and detection of electromagnetic waves.
The electromagnetic spectrum describes a different range of electromagnetic waves. These $\text{EM}$ waves are a special type of wave that can travel without a medium.
Electromagnetic waves are named like this due to the fact that they have both an electric and a magnetic component. In a vacuum, $\text{EM}$ waves always travel at the same speed i.e. the speed of light. So, other $\text{EM}$ waves besides light are infrared, ultraviolet, radio waves, and microwaves.
Therefore radio and television both are based on $\text{EM}$ wave properties. Other options like lasers, reactors, and computers are not guided by $\text{EM}$ waves.

Given, frequency of $EM$ waves
$v=8.196 \times 10^6 Hz$
velocity of EM waves $(v)=3 \times 10^8 m / s$
Wavelength of $EM$ waves $\lambda=\frac{ v }{ v }$
$=\frac{3 \times 10^8}{8.196 \times 10^6}$
$=36.60 m$
$=3660 \ cm$

Electric field and magnetic field vectors for an electromagnetic wave are cross $-$ field vectors.
So, the direction of an electromagnetic wave is given by the product of electric field vector and magnetic field vector.
According to the question, electric field vector is directed upwards and $\text{EM}$ wave is directed towards North. So, according to the right $-$ hand thumb rule, the magnetic field vector points towards the East.

The propagation constant can be written as
$\text{K}=\frac{2pi}{\lambda}=\frac{60284}{6284\times10^{-8}}=10^5\text{cm}^{-1}$

$\overrightarrow{E}$ and $\overrightarrow{B}$ are mutually perpendicular to each other and are in phase i.e., they become zero and minimum at the same place and at the same time.

They vary with time following a wave function $($sinuosoidal$)$ and average value of these function is zero and also we can see in figure they are mutually perpendicular and also perpendicular to direction of propagation.

When an electromagnetic wave strikes a material surface, it transports the momentum, as well as the energy, to the surface. The striking electromagnetic wave exerts pressure on the surface. The total energy transferred to the surface by the electromagnetic wave is given by $\text{E}=\text{pc}$ Therefore, $\text{p}\neq0,\text{ E}\neq0$

From electromagnetic spectrum, frequencies of $\gamma-$rays is greater than frequency of $X-$rays. Frequency of Xrays is greater than frequency of ultraviolet rays.

Energy of a photon,
$\text{E} = \text{hv} = \frac {\text{hc}}{\lambda}.$
$\text{E}\propto\frac{1}{\lambda}.$
When the wavelength of electromagnetic radiation is doubled, the energy of the photons is halved.

For a linearly polarised, plane electromagnetic wave,
$E = E _0 \sin \omega\left( t -\frac{ x }{ c }\right)$
$B = B _0 \sin \omega\left( t -\frac{ x }{ c }\right)$
The average value of either $E$ or Bover a cycle is zero $($average of $\sin (\theta)$ over a cycle is zero$).$
Also the electric energy density $\left(U_E\right)$ and magnetic energy density $\left(U_B\right)$ are equal.
$u _{ E }=\frac{1}{2} \in_0 E ^2=\frac{ B ^2}{2 \mu_0}= u _{ B }$
Energy can be found out by integrating energy density over the entire volume of full space. As the energy of the electromagnetic wave is equally shared between electric and magnetic field so their average values will also be equal.

By Maxwell
$I _{ d }=\frac{ EdE }{ dt }$
$d E$ is electric field
$I_d$ is displacement current per unit area.
Hence changing electric field gives displacement current.

The average of $\sin\theta$ and $\cos\theta$ for whole cycle is is zero.
Step $1:$ Analyzing the average value of Kinetic energy.
Kinetic Energy is always a positive quantity, therefore its average will also be a positive quantity.
Step $2:$ Finding the average of electric and the magnetic field.
The equations for the electric field and the magnetic field are given as

1. The associated magnetic field is given as $\text{B}=\frac{1}{\text{c}}\text{k}\times\text{E}=\frac{1}{\omega}(\hat{\text{k}}\times\text{E})$.
2. The electromagnetic field can be written in terms of the associated magnetic field as $\text{E}=\text{c}(\text{B}\times\hat{\text{k}})$.
3. $\hat{\text{k}}.\text{E}=0,\hat{\text{k}}.\text{B}=0.$

1. The direction of propagation of an eletromagnetic wave is always along the direction of vector product $\vec{\text{E}}\times\vec{\text{B}}$. Refer to Figure.

2. $\vec{\text{E}}=\text{E}\hat{\text{i}}=\text{cB}(\hat{\text{j}}\times\hat{\text{k}})=\text{c}(\text{B}\hat{\text{j}}\times\text{k})=\text{c}(\vec{\text{B}}\times\hat{\text{k}})$
3. $\hat{\text{k}}.\vec{\text{E}}=\hat{\text{k}}.(\text{E}\hat{\text{i}})=0,\vec{\text{k}}.\vec{\text{B}}=\vec{\text{k}}.(\text{B}\hat{\text{j}})=0$
4. $\hat{\text{k}}\times\vec{\text{E}}=\hat{\text{k}}\times(\text{E}\hat{\text{i}})=\text{E}(\hat{\text{k}}\times\hat{\text{i}})=\text{E}\hat{\text{j}}$ and $\hat{\text{k}}\times\vec{\text{B}}=\hat{\text{k}}\times(\text{B}\hat{\text{j}})=\text{B}(\hat{\text{k}}\times\hat{\text{j}})=-\text{B}\hat{\text{i}}$.

The relation between $E _0$ and $B _0$ id given by $\frac{\text{E}_0}{\text{B}_0}=\text{c}\ ....(\text{i})$
Here, $c =$ Speed of the electromagnetic wave,
The relation between $\omega ($the angular frequency$)$ and $k\ ($wave number$),$
$\frac{\omega}{\text{k}}=\text{c}\ ...(\text{ii})$
Therefore, from $(i)$ and $(ii),$ we get
$\frac{\text{E}_0}{\text{B}_0}=\frac{\omega}{\text{k}}=\text{c}$
$\text{E}_0\text{k}=\text{B}_0\omega$

According to Maxwell's hypothesis, changing of electric field gives rise to Magnetic field.
We know that $F = qE$,, where $F$ is force and $E$ is electric field.
We can relate magnetic field and force by $F = qvB$, where $v$ is velocity and $B$ is the magnetic field.
Therefore we can obtain magnetic field by changing electric field.

Velocity of a wave is given by:
$\text{v}=\frac{\text{E}}{\text{B}}$
Hence wave velocity change in both the cases.
Frequency of the wave remains the same.
Using $\text{v}=\text{f}\lambda,$ it can be concluded that both $\lambda_1$ and $\lambda_2$ are variable.

Velocity of wave $=$ wavelength $\times $ frequency
$\text{v}=3\times10^8\frac{\text{m}}{\text{s}}$
$\lambda=7500\text{A}=7500\times10^{-10}\text{m}$
$\text{f}=\frac{3\times10^8}{7500\times10^{-10}}=4\times10^{14}\text{Hz}$

The emitted $X-$rays transfer energy to the material on which it is falling.

The direction of propagation of electromagnetic wave is perpendicular to the variation of electric field $\overrightarrow{\text{E}}$ as well as to the magnetic field $\overrightarrow{\text{B}}$

The ionosphere can reflect electromagnetic waves of frequency less than $40MHz$ but not of frequency more than $40MHz.$

The frequency range of Gamma rays is $3 \times 10^{18}$ to $5 \times 10^{22} Hz$. These rays have a wavelength of $6 \times 10^{-13}$ to $10^{-10} m$. Gamma rays are produced in nuclear reactions and are also emitted by radioactive nuclei.

Light wave is an electromagnetic wave in which $E$ and $B$ are at right angles to each other as well as at right angles to the direction of wave propagation. So from the given information in the question, the direction of $B$ vector is in positive $z$ direction.

According to Maxwell's hypothesis, a displacement current will flow through a capacitor when the potential difference across its plates is varying. Thus a varying electric field will exist between the plates and this displacement current is same in magnitude to the current flowing in outer circuit. When a $D.C$ voltage applied across its plates, constant voltage appears across its plates and so there will be no displacement current flowing through the capacitor. Thus the displacement current will flow when the potential is increasing with time.

Wave number $=\frac{1}{\text{wavelength}}$
$=\frac{1}{5000\times10^{-10}}$
$=2\times10^6\text{m}^{-1}$

Given: Electric field $=60 v / m$
$C =3 \times 10^8 m / s ^2$
To find: Magnetic field
Solution:
We know, $C =\frac{ E _0}{B_0}$
Therefore, $B _0=\frac{ E _0}{ C }$
$\frac{60}{3 \times 10^8}=2 \times 10^7 T$

The ozone layer prevents most harmful $UV$ wavelengths of ultraviolet light $(UV$ light$)$ from passing through the Earth's atmosphere. These wavelengths cause skin cancer, sunburn and cataracts, which were projected to increase dramatically as a result of thinning ozone, as well as harming plants and animals.

Maximum rate of energy flow, $S = E _0 \times H _0$
Given, $\text{E}_0=\frac{100\text{V}}{\text{m}},\text{H}_0=\frac{0.265\text{A}}{\text{m}}$
$\therefore\text{S}=100\times0.265=\frac{26.5\text{W}}{\text{m}^2}$​

The direction of $EM$ wave is given by the direction of $\overrightarrow{\text{E}}\times\overrightarrow{\text{B}}$

The correct combination is $\rightarrow Vm = Vi = Vu$. This is because, in vacuum, all the electromagnetic waves in question will travel at the same speed. The speed with which they travel in vacuum is the speed of light. $( c =3 \times 108 m / s ).$

Ultraviolet $(UV)$ radiations in large quantities are highly harmful to humans. These rays in solar radiation on reaching earth are absorbed by the ozone layer in the atmosphere. $UV$ rays are produced by special lamps such as mercury and from arc lamps and by very hot bodies like the sun.

$\text{UHF}$ stands for Ultra high frequency. Cellular phones used radio waves to transmit voice communication in the Ultra high$-$frequency Band. The $\text{UHF}$ band extends from $900 MHz$ to $5 \times 109 Hz$ or $5000 MHz$. Radio waves are produced by oscillating circuits having an inductor and capacitor.

Momentum of a photon
$=\frac{\text{h}}{\lambda}=\frac{\text{h}}{\frac{\text{c}}{\text{v}}}=\frac{\text{hv}}{\text{c}}=\frac{\text{E}}{\text{c}}$
Momentum over unit area
$=\frac{\text{E}}{\text{Ac}}=\frac{\text{I}}{\text{c}}\Big[\text{I}=\frac{\text{E}}{\text{A}}\text{ For wave}\Big]$
Since surface is non reflecting, final momentum of photon $= 0,$ change in momentum $=\frac{\text{I}}{\text{c}}$
So, force per unit area $=\frac{\text{I}}{\text{c}}$
Pressure of radiation $=\frac{\text{I}}{\text{c}}$