Electromagnetic Waves Test

Result

Electromagnetic Waves Test - 30

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

Which one of the following is the primary effect of UV radiation caused due to depletion of ozone layer?

A
Heart attack

B
Skin cancer

C
High fever

D
All of these

E
None of these

Solution

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.
Question 2
1 / -0

Infrared radiation are detected by

A
spectrometer

B
pyrometer

C
nanometer

D
photometre

Solution

Infrared radiation is detected by $$photometer$$
Hence$$,$$ option $$(D)$$ IS correct$$.$$
Question 3
1 / -0

A parallel plate capacitor of plate separation 2 mm is connected in an electric circuit having source voltage 400. What is the value of the displacement current for $$10^{-6}$$ s, if plate area is 60 $$cm^2$$

A
$$1.062 \times 10^{-2} \ A$$

B
$$2.062 \times 10^{-2} \ A$$

C
$$3.062 \times 10^{-2} \ A$$

D
$$5.062 \times 10^{-2} \ A$$

Solution
Question 4
1 / -0

An electromagnetic wave emitted by source travels $$21$$km to arrive at a receiver. The wave while travelling in another path is reflected from a surface at $$19$$km away and further travels $$12$$km to reach the same receiver. If distributive inference occurs at the receiving end, the wavelength of the wave is

A
$$0.5$$km

B
$$20$$km

C
$$5$$km

D
$$10$$km

Solution
Question 5
1 / -0

The electric field part of an electromagnetic wave in a medium is represented by $$Ex=0$$

$$Ey= 2.5 N/C ((2*10^6 rad/m)t - (*10^-2 rad/s) x)$$

$$Ez=0$$ the wave is

A
Moving along X direction with frequency 10^6 Hz and wavelength 100m

B
Moving along X direction with frequency 10^6 Hz and wavelength 200m

C
Moving along - X direction with frequency 10^6 Hz and wavelength 100m

D
Moving along y direction with frequency 2*10^6 Hz and lwavelength 100m

Solution
Question 6
1 / -0

The electric field of a plane electromagnetic wave is given by
$$\overrightarrow { y }=E_0 \hat{i} cos(kz)(\omega t) $$
The corresponding magnetic field $$\overrightarrow { B }$$ is then given by:

A
$$\overrightarrow { B }=\dfrac{E_0}{c} \hat{i}sin(kz)cos(\omega t)$$

B
$$\overrightarrow { B }=\dfrac{E_0}{c} \hat{j}sin(kz)cos(\omega t)$$

C
$$\overrightarrow { B }=\dfrac{E_0}{c} \hat{k}sin(kz)cos(\omega t)$$

D
$$\overrightarrow { B }=\dfrac{E_0}{c} \hat{j}cos(kz)sin(\omega t)$$

Solution

$$\because\overrightarrow { E }\times \overrightarrow { B }||\overrightarrow { V }$$
Given that wave is propagating along positive z-axis and $$\overrightarrow { E }$$ along positive x-axis. Hence $$\overrightarrow { B }$$ along y-axis.
From Maxwel equation
$$\overrightarrow { V }\times \overrightarrow { E }=-\dfrac{\partial B}{\partial t}$$
i.e. $$\dfrac{\partial E}{\partial Z}=-\dfrac{\partial B}{\partial t} and B_0=\dfrac{E_0}{C}$$
so, $$\overrightarrow {B} = \dfrac{\overrightarrow{E_{0}}}{c}\hat{j}sin(kz)cos(\omega t)$$
Question 7
1 / -0

Some devices and electromagnetic wave are given in Column -I and Column - II, match the device with electromagnetic wave work:
Column - I Column - II
(A) Mobile
(B) Sonar
(C) Radar
(D) Optical fiber (P) Microwave
(Q) IR
(R) Radio wave
(S) Ultra sound

A
$$(A \rightarrow S); (B \rightarrow Q), (C \rightarrow P), (D \rightarrow R)$$

B
$$(A \rightarrow Q); (B \rightarrow S), (C \rightarrow P), (D \rightarrow R)$$

C
$$(A \rightarrow Q); (B \rightarrow S), (C \rightarrow R), (D \rightarrow P)$$

D
$$(A \rightarrow S); (B \rightarrow Q), (C \rightarrow R), (D \rightarrow P)$$

Solution

$$1)Mobile-IR;$$
IR wireless is the use of wireless technology in devices or systems that convey data through infrared (IR) radiation. Infrared is electromagnetic energy at a wavelength or wavelengths somewhat longer than those of red light.the Infrared feature or IR LED as is popularly known, smartphones can now be used as a remote controller for TVs, set top boxes, AC etc

$$2)SONAR-Ultrasound$$
The ultrasonic sensor uses sonar to determine the distance to an object.

$$3)Radar-Microwave$$
Microwave Radar Sensor module has been designed as an alternative to the common PIR motion sensors widely used in burglar alarms and security lights. Like the PIR sensor this sensor also detects only movements within its detection range.

$$4)Optical Fiber-Radio waves$$
Radio over fiber (RoF) or RF over fiber (RFoF) refers to a technology whereby light is modulated by a radio frequency signal and transmitted over an optical fiber link. Main technical advantages of using fiber optical links are lower transmission losses and reduced sensitivity to noise and electromagnetic interference compared to all-electrical signal transmission.

$$(A \rightarrow Q) ; (B \rightarrow S), (C \rightarrow P) , (D \rightarrow R)$$
Question 8
1 / -0

The amplitude of the sinusoidally oscillating electric field of a plane wave is 60v /m. Then the amplitude of the magnetic field is

A
$$12 \times 10 ^ { -7 } \mathrm { T }$$

B
$$6 \times 10 ^ { -7 } \mathrm { T }$$

C
$$6 \times 10 ^ { -8 } \mathrm { T }$$

D
$$2 \times 10 ^ { -7 } T$$

Solution

$$\textbf{Given}$$ : Electric field = 60 v /m
C = 3$$\times10^{8}$$ m/s$$^{2}$$
$$\textbf{To find}$$ : Magnetic field

$$\textbf{Solution}$$ :
We know, C = $$\dfrac{E_{o}}{B_{o}}$$
Therefore, $$B_{o}$$ = $$\dfrac{E_{o}}{C}$$ = $$\dfrac{60}{3\times10^{8}}$$
= 2$$\times10^{-7}$$ T

$$\textbf{Hence D is the correct option.}$$
Question 9
1 / -0

The intensity of electromagnetic wave at a distance of 1$$\mathrm { km }$$ from a source of power $$12.56kW$$ is

A
$$10 ^ { - 3 } \mathrm { Wm } ^ { - 2 }$$

B
$$4 \times 10 ^ { - 3 } \mathrm { W } \mathrm { m } ^ { - 2 }$$

C
$$12.56 \times 10 ^ { - 3 } \mathrm { W } \mathrm { m } ^ { 2 }$$

D
$$1.256 \times 10 ^ { - 3 } \mathrm { W } \mathrm { m } ^ { 2 }$$

Solution
Question 10
1 / -0

The electric component of an electromagnetic wave (in SI units) are given by
$$E_x=10^2 sin [\pi (9 \times 10^{14} t-3 \times 10^6z)]$$
$$E_y=0,E_z=0$$ find the inensity of this radiation.

A
$$13.3 Wm^{-2}$$

B
$$0.133 Wm^{-2}$$

C
$$1.33 Wm^{-2}$$

D
$$13.3 \times 10^{-12} Wm^{-2}$$

Solution

Intensity is given by, $$I = c\epsilon_{\circ}E_{rms}$$

Now, for sinusoidal wave,
$$E_{rms} = \dfrac{E_{\circ}}{\sqrt{2}}$$

Given: $$E_{\circ} = 10^2$$

$$\therefore I = 3 \times 10^8\times8.85\times10^{-12}\times\dfrac{10^4}{2} = 13.3$$ $$W/m^2$$

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

Column - I	Column - II
(A) Mobile (B) Sonar (C) Radar (D) Optical fiber	(P) Microwave (Q) IR (R) Radio wave (S) Ultra sound

Electromagnetic Waves Test - 30

Result

Electromagnetic Waves Test - 30

Score

-

Rank

-

SHARING IS CARING

Question 1

Heart attack

Skin cancer

High fever

All of these

None of these

Solution

Question 2

spectrometer

pyrometer

nanometer

photometre

Solution

Question 3

$$1.062 \times 10^{-2} \ A$$

$$2.062 \times 10^{-2} \ A$$

$$3.062 \times 10^{-2} \ A$$

$$5.062 \times 10^{-2} \ A$$

Solution

Question 4

$$0.5$$km

$$20$$km

$$5$$km

$$10$$km

Solution

Question 5

Moving along X direction with frequency 10^6 Hz and wavelength 100m

Moving along X direction with frequency 10^6 Hz and wavelength 200m

Moving along - X direction with frequency 10^6 Hz and wavelength 100m

Moving along y direction with frequency 2*10^6 Hz and lwavelength 100m

Solution

Question 6

$$\overrightarrow { B }=\dfrac{E_0}{c} \hat{i}sin(kz)cos(\omega t)$$

$$\overrightarrow { B }=\dfrac{E_0}{c} \hat{j}sin(kz)cos(\omega t)$$

$$\overrightarrow { B }=\dfrac{E_0}{c} \hat{k}sin(kz)cos(\omega t)$$

$$\overrightarrow { B }=\dfrac{E_0}{c} \hat{j}cos(kz)sin(\omega t)$$

Solution

Question 7

$$(A \rightarrow S); (B \rightarrow Q), (C \rightarrow P), (D \rightarrow R)$$

$$(A \rightarrow Q); (B \rightarrow S), (C \rightarrow P), (D \rightarrow R)$$

$$(A \rightarrow Q); (B \rightarrow S), (C \rightarrow R), (D \rightarrow P)$$

$$(A \rightarrow S); (B \rightarrow Q), (C \rightarrow R), (D \rightarrow P)$$

Solution

Question 8

$$12 \times 10 ^ { -7 } \mathrm { T }$$

$$6 \times 10 ^ { -7 } \mathrm { T }$$

$$6 \times 10 ^ { -8 } \mathrm { T }$$

$$2 \times 10 ^ { -7 } T$$

Solution

Question 9

$$10 ^ { - 3 } \mathrm { Wm } ^ { - 2 }$$

$$4 \times 10 ^ { - 3 } \mathrm { W } \mathrm { m } ^ { - 2 }$$

$$12.56 \times 10 ^ { - 3 } \mathrm { W } \mathrm { m } ^ { 2 }$$

$$1.256 \times 10 ^ { - 3 } \mathrm { W } \mathrm { m } ^ { 2 }$$

Solution

Question 10

$$13.3 Wm^{-2}$$

$$0.133 Wm^{-2}$$

$$1.33 Wm^{-2}$$

$$13.3 \times 10^{-12} Wm^{-2}$$

Solution

User

Question Analysis

My Perfomance

Score

-

Rank

-

Results Announcement on: coming Monday

Stay Tuned: We’ll update you on your result via email or SMS.