CBSE Questions for Class 12 Medical Physics Electromagnetic Waves Quiz 1 - MCQExams.com

Some radio waves of frequency of about $$1.5\times 10^9$$ Hz was received by a radio-telescope from distance star. If the speed of the waves is $$3\times 10^5$$ km/s, then the wave-length of the wave will be?
  • $$0.1$$ m
  • $$0.6$$ m
  • $$0.2$$ m
  • $$0.46$$ m
The energy of photon of electromagnetic radiation of wavelength$$=2000\mathring{A}$$ is?
  • $$1.76\times 10^{-18}$$J
  • $$0.99\times 10^{-18}$$J
  • $$0.54\times 10^{-18}$$J
  • $$0.63\times 10^{-18}$$J
A radio wave of intensity l is reflected by a surface. The intensity (I), if pressure exerted on the surface is $$2\times 10^{-8}N/m^2$$, will be?
  • $$3 N/m^2$$
  • $$4 N/m^2$$
  • $$6 N/m^2$$
  • $$7 N/m^2$$
A TV tower has a height of $$100$$m. The area covered by the TV broadcast, if radius of the earth is $$6400$$ km, will be?
  • $$380\times 10^7m^2$$
  • $$402\times 10^7m^2$$
  • $$595\times 10^7m^2$$
  • $$440\times 10^7m^2$$
The current option, if speed of gamma rays, X-rays and microwaves are $$v_g, v_x$$ and $$v_m$$ respectively will be?
  • $$v_g > v_x > v_m$$
  • $$v_g < v_x < v_m$$
  • $$v_g > v_x < v_m$$
  • $$v_g = v_x = v_m$$
Arrange the following electromagnetic radiations per quantum in the order of increasing energy:
A: Blue light
B: Yellow light
C: X-ray
D: Radiowave 
  • D,B,A,C
  • A,B,D,C
  • C,A,B,D
  • B,A,D,C
What is the displacement current between the square plate of side 1 cm of a capacitor, if electric field between the, plates is changing at the rate of 3 x $$10^6 V_m^{-1}S^{-1}$$? 
  • 2.7 x $$10^{-9}$$ A
  • 3.2 x $$10^{-9}$$ A
  • 4.2 x $$10^{-9}$$ A
  • 4.0 x $$10^{-9}$$ A
Choose the correct equation of maxwell ampere circuital law:
  • $$\oint \overline { B } \cdot \overline { d l } = \mu _ { 0 } \varepsilon _ { 0 } \frac { d \phi _ { E } } { d t }$$
  • $$\oint \overline { B } \cdot \overline { d l } = \mu _ { 9 } + \varepsilon _ { 0 } \frac { d \phi _ { E } } { d t }$$
  • $$\oint \vec { B } \cdot \overline { d l } = \mu _ { 0 } \left( i _ { c } + \varepsilon _ { 0 } \frac { d \phi _ { E } } { d t } \right)$$
  • $$\oint \overline { B } \cdot \overline { d l } = \mu _ { 0 } i _ { C } + \varepsilon _ { 0 } \frac { d \phi _ { \varepsilon } } { d t }$$
Which of the following sources of light is different from others
  • Sunlight
  • White light
  • Light from a bulb
  • Sodium light
Which wavelength of sun is used finally as electric energy? 
  • Radio waves
  • Infrared waves
  • Visible light
  • Micro waves
Magnetic field in a plane electromagnetic wave is given by 
$$ \overrightarrow{B} = B_0 sin (kx + \omega t) \hat{j} T $$
Expression for corresponding electric field will be :
Where c is speed of light.
  • $$ \overrightarrow {E} = B_0 c\sin (kx + \omega t) \hat{k} V/m $$
  • $$ \overrightarrow{E} = \dfrac{B_0}{c} \sin (kx + \omega t) \hat{k} V/m $$
  • $$ \overrightarrow {E} = - B_0 c \sin (kx + \omega t) \hat{k} V/m $$
  • $$ \overrightarrow{E} = B_0 c \sin (kx - \omega t) \hat{k} V/m $$
Match the List -I (Phenomenon associated with electromagnetic radiation) with List - II (Part of electromagnetic spectrum) and select the correct code from the choices given below the

List - I

List - II
I
Doublet of sodium
A
Visible radiation
II
Wavelength corresponding to temperature associated with the isotropic radiation filling all space
B
Microwave
III
Wavelength emitted by atomic hydrogen in interstellar space
C
Short radiowave
IV
Wavelength of radiation arising from two close energy levels in hydrogen
D
X-rays
  • (I)-(A), (II)-(B), (III)-(B), (IV)-(C)
  • (I)-(D), (II)-(C), (III)-(A), (IV)-(B)
  • (I)-(B), (II)-(A), (III)-(D), (IV)-(A)
  • (I)-(A), (II)-(B), (III)-(C), (IV)-(D)
Out of the following options which one can be used to produce a propagating electromagnetic wave?
  • A charge moving at constant velocity
  • A stationary charge
  • A chargeless particle
  • An accelerating charge
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Both Assertion and Reason are incorrect
IF $$v_s, v_x$$ and $$v_m$$ are the speeds of gamma rays X-rays and microwaves respectively in vacuum, then:
  • $$v_s > v_x > v_m$$
  • $$v_s < v_x < v_m$$
  • $$v_s < v_x > v_m$$
  • $$v_s = v_x = v_m$$
The frequency order for X-rays(A), $$\gamma $$ rays(B), UV rays(C) is
  • $$B>A>C$$
  • $$A>B>C$$
  • $$C>B>A$$
  • $$A>C>B$$
Displacement current is continuous:
  • when electric field is changing in the circuit
  • when magnetic field is changing in the circuit
  • in both types of fields
  • through wires and resistance only
Which of the following waves is used in Raman spectroscopy?
  • UV
  • $$x-$$rays
  • $$\gamma-$$ rays
  • IR
Which of the following rays is emitted  by a human body?
  • x-rays
  • visible rays
  • uvrays
  • IR rays
  • none of these
Speed of electromagnetic waves is the same:
  • for all wavelengths
  • in all media
  • for all intensities
  • for all frequencies
Infrared radiation was discovered in 1860  by
  • William Wallaston
  • William Herschel
  • William Roentgen
  • Thomas Young
Choose the correct answer from the alternatives given.
Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor
  • increases
  • decreases
  • increases or decreases
  • is zero
In case of the electromagnetic waves the angle between the electric and magnetic field vectors is
  • $$\pi$$
  • $$\pi/2$$
  • zero
  • none of these
The waves relevant to telecommunications are
  • visible light
  • infrared
  • ultraviolet
  • microwave
Radio waves of constant amplitude can be generated with 
  • filter
  • rectifier
  • FET
  • oscillator
Electromagnetic radiation of wave length 0.01 mm belong to ........................ region
  • Visible
  • Ultraviolet
  • Infrared
  • None of these
When light propagates in vacuum there is an electric field and a magnetic field. These fields
  • are constant in time
  • have zero average value
  • are perpendicular to the direction of propagation of light.
  • are mutually perpendicular
The displacement current flows in the dielectric of a capacitor when the potential difference across its plates
  • becomes zero
  • has assumed a constant value
  • is increasing with time
  • is decreasing with time
Which colour of light travels fastest in any medium except air?
  • Red
  • Violet
  • Blue
  • Orange
The waves related to tele-communication are
  • infrared
  • visible light
  • microwaves
  • ultraviolet rays
Choose the correct answer from the alternatives given.
The conduction current is the same as displacement current when the source is
  • AC only
  • DC only
  • both AC and DC
  • neither AC nor for DC
The nature of electromagnetic wave is:
  • longitudinal
  • longitudinal stationary
  • transverse
  • transverse stationary
The frequency from $$3\times { 10 }^{ 9 }Hz$$ to $$3\times { 10 }^{ 10 }Hz$$ is
  • high frequency band
  • super high frequency band
  • ultra high frequency band
  • very high frequency band
Identify the most notable difference between a ultraviolet wave and a light wave ?
  • Speed
  • Refractive index
  • Reflectivity
  • Amplitude
  • Frequency
Select wrong statement from the following:
Electromagnetic waves
  • are transverse
  • travel with same speed in all media
  • travel with the speed of light
  • are produced by accelerating charge
Electromagnetic waves do not transport
  • energy
  • charge
  • momentum
  • information
Out of the following , whose velocity is equal to that of light?
  • of $$\beta$$ rays
  • of sound waves
  • of ultrasonic waves
  • none of these
Name the seven prominent colours of the white light spectrum in order of their increasing frequencies
  • Violet, Indigo, Blue, Green, Yellow, Orange, Red
  • Red, Orange, Yellow, Green, Blue, Indigo, Violet
  • Red, Orange, Violet, Yellow, Green, Blue, Indigo
  • Orange, Yellow, Green, Red, Blue, Indigo, Violet
Write the approximate wavelengths for red light.
  • $$1000A^o$$
  • $$2000A^o$$
  • $$4000A^o$$
  • $$8000A^o$$
What is the range of wavelength of the spectrum of white light in $$A^o$$ ?
  • $$4000A^o$$ to $$5000A^o$$
  • $$5000A^o$$ to $$6000A^o$$
  • $$6000A^o$$ to $$8000A^o$$
  • All the above
Write the approximate wavelengths for blue light?
  • $$800A^o$$
  • $$1600A^o$$
  • $$3200A^o$$
  • $$4800A^o$$
A wave has wavelength $$50A^o$$. Name the wave.
  • X-ray
  • Gamma ray
  • Radio waves
  • Micro waves
Which radiation is used for satellite communication?
  • Micro waves
  • X rays
  • Gamma rays
  • Infra red rays
The wavelengths for the light of red and blue colours are roughly $$7.8\times 10^{-7}m$$ and $$4.8\times 10^{-7}m$$ respectively. Which colour has the greater speed in glass?
  • Red light
  • Violet light
  • Yellow light
  • All colors have same speed
What is the range of wavelength of the spectrum of white light in $$nm$$?
  • $$400nm$$ to $$500nm$$
  • $$500nm$$ to $$600nm$$
  • $$600nm$$ to $$800nm$$
  • All the above
Name color/s of the spectrum of white light which have wavelength longer than blue light.
  • Green
  • Yellow
  • Red
  • All the above
Name the rays or waves of wavelength nearly $$0.1nm$$.
  • IR rays
  • UV rays
  • Gamma rays
  • X-rays
Name the region beyond the red end of the spectrum.
  • Ultra red
  • infra red
  • dark red
  • light red
The most energetic electromagnetic radiations are:
  • microwaves
  • ultraviolet waves
  • $$X$$-rays
  • gamma rays
Name the high energetic invisible electromagnetic wave which helps in the study of structure of crystals.
  • $$X$$-rays
  • Cathod rays
  • Gamma rays
  • All of the above
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